11 Units · Beginner-Friendly Notes · Step-by-Step Worked Examples · Interactive Quiz + Flashcards · Full-Length Practice Exam · Saved Progress
Based on this guide's real question bank — 440 practice questions across 11 units. Slide to match your situation.
Two intersecting lines: ∠1 & ∠3 are vertical (equal); ∠1 & ∠2 form a linear pair (sum 180°).
A transversal crossing parallel lines. Alternate interior angles (3 & 6) are equal; same-side interior (3 & 5) sum to 180°.
Triangle interior angles always add to 180°. The exterior angle (d) equals a + b.
Matching tick marks show corresponding congruent parts. Here two sides match (SAS needs the angle BETWEEN them; the shared side gives Reflexive).
DE ∥ AC creates a smaller similar triangle: every length in △BDE is k times △BAC. Lengths scale by k, areas by k², volumes by k³.
Right triangle: a² + b² = c². For angle θ: sin = opp/hyp, cos = adj/hyp, tan = opp/adj.
The quadrilateral family: each arrow adds properties. A square inherits EVERYTHING from both the rectangle and the rhombus.
Inscribed angle = ½ its arc. Central angle = the full arc. An angle in a semicircle is 90°.
On the coordinate plane: distance = √[(Δx)²+(Δy)²], slope = rise/run, midpoint = average of coordinates.
One point, three images: reflections keep one coordinate, 180° negates both. Memorize by the quadrant the image lands in.
A cone (or pyramid) is exactly ⅓ of the cylinder (or prism) with the same base and height.
Two lines intersect. One angle measures 72°. What is the measure of its vertical angle?
Vertical angles are always congruent (equal). The vertical angle is also 72°.
Two complementary angles are such that one is twice the other. What is the larger angle?
x + 2x = 90 → 3x = 90 → x = 30. The larger angle is 2x = 60°.
Two angles are supplementary. One is 3 times the other. The smaller angle is
x + 3x = 180 → 4x = 180 → x = 45°.
An inscribed angle in a semicircle (subtending a diameter) measures
An angle inscribed in a semicircle is always a right angle, 90°.
Two complementary angles are such that one is 4 times the other. The larger angle is
x + 4x = 90 → 5x = 90 → x = 18; larger = 4(18) = 72°.
∠1 and ∠2 are vertical angles. If ∠1 = (2x + 10)° and ∠2 = 50°, then x =
Vertical angles are equal: 2x + 10 = 50 → 2x = 40 → x = 20.
The supplement of an angle is 3 times the angle. The angle is
x + 3x = 180 → 4x = 180 → x = 45°.
M is the midpoint of ̅AB. If AM = 2x + 1 and MB = 11, then x =
AM = MB → 2x + 1 = 11 → 2x = 10 → x = 5.
Ray BD is in the interior of ∠ABC. If ∠ABD = 35° and ∠DBC = 55°, then m∠ABC =
Angle Addition: 35 + 55 = 90°.
If an angle is congruent to its own complement, the angle measures
x = 90 − x → 2x = 90 → x = 45°.
Adjacent angles ∠AOB = (3x)° and ∠BOC = (2x)° together form a right angle. Then x =
3x + 2x = 90 → 5x = 90 → x = 18.
An angle is 40° more than its complement. The angle measures
x = (90 − x) + 40 → 2x = 130 → x = 65°.
Two angles form a linear pair. One angle is 24° more than twice the other. What is the measure of the larger angle?
x + (2x + 24) = 180 → 3x = 156 → x = 52. Larger = 2(52) + 24 = 128°.
∠A and ∠B are vertical angles with m∠A = (5x − 17)° and m∠B = (3x + 25)°. What is m∠A?
Vertical angles are equal: 5x − 17 = 3x + 25 → x = 21 → m∠A = 5(21) − 17 = 88°.
B is between A and C. AB = 2x + 3, BC = 3x − 1, and AC = 42. What is the length of AB?
(2x+3) + (3x−1) = 42 → 5x + 2 = 42 → x = 8 → AB = 2(8) + 3 = 19.
M is the midpoint of segment AB. AM = 5x − 4 and MB = 3x + 10. What is the length of AB?
5x − 4 = 3x + 10 → x = 7 → AM = 31 → AB = 2(31) = 62.
Ray OC bisects ∠AOB. If m∠AOC = (3x + 5)° and m∠COB = (5x − 13)°, find m∠AOB.
Bisected halves are equal: 3x + 5 = 5x − 13 → x = 9 → each half = 32° → whole = 64°.
The complement of an angle is one-fourth of its supplement. Find the angle.
90 − x = ¼(180 − x) → 360 − 4x = 180 − x → 180 = 3x → x = 60°.
Three angles measuring (2x)°, (3x)°, and (4x)° together form a straight line. The largest of the three angles is
2x + 3x + 4x = 180 → x = 20 → largest = 4(20) = 80°.
An angle exceeds its supplement by 36°. The angle measures
x − (180 − x) = 36 → 2x = 216 → x = 108°.
In the diagram, two lines intersect. Find x.
The labeled angles are vertical, so they are equal: 3x + 10 = 70 → x = 20.
Ray OC lies inside right angle AOB. If m∠COB = 25° and m∠AOC = (2x + 5)°, find x.
Angle Addition: (2x + 5) + 25 = 90 → 2x = 60 → x = 30.
An angle is 3° more than twice its complement. The angle measures
x = 2(90 − x) + 3 → x = 183 − 2x → 3x = 183 → x = 61°.
Two angles in a linear pair are in the ratio 4 : 5. The smaller angle measures
4x + 5x = 180 → x = 20 → smaller = 80°.
B is the midpoint of AC. If AB = 3x − 7 and AC = 4x + 6, then AC =
AC = 2·AB: 4x + 6 = 2(3x − 7) → 4x + 6 = 6x − 14 → x = 10 → AC = 46.
Vertical angles measure (7x − 9)° and (4x + 27)°. What is the SUPPLEMENT of either angle?
7x − 9 = 4x + 27 → x = 12 → angle = 75° → supplement = 105°.
Three angles around a point measure (2x)°, (3x)°, and (4x)°. The largest angle is
Angles around a point total 360°: 9x = 360 → x = 40 → largest = 160°.
An angle exceeds its complement by 22°. The angle measures
x − (90 − x) = 22 → 2x = 112 → x = 56°.
Two angles are complementary. One measures 17°. The other measures
Complementary → 90 − 17 = 73°.
Two angles are complementary. One measures 41°. The other measures
Complementary → 90 − 41 = 49°.
Angle A and angle B form a linear pair. If m∠A = 38°, then m∠B =
Linear pair → 180 − 38 = 142°.
Two angles are complementary. One measures 23°. The other measures
Complementary → 90 − 23 = 67°.
Angle A and angle B form a linear pair. If m∠A = 66°, then m∠B =
Linear pair → 180 − 66 = 114°.
Angle A and angle B form a linear pair. If m∠A = 95°, then m∠B =
Linear pair → 180 − 95 = 85°.
Two angles are complementary. One measures 29°. The other measures
Complementary → 90 − 29 = 61°.
Angle A and angle B form a linear pair. If m∠A = 81°, then m∠B =
Linear pair → 180 − 81 = 99°.
Two angles are complementary. One measures 47°. The other measures
Complementary → 90 − 47 = 43°.
Angle A and angle B form a linear pair. If m∠A = 54°, then m∠B =
Linear pair → 180 − 54 = 126°.
Two angles are complementary. One measures 34°. The other measures
Complementary → 90 − 34 = 56°.
Angle A and angle B form a linear pair. If m∠A = 72°, then m∠B =
Linear pair → 180 − 72 = 108°.
Alternate interior angles measure (2x + 10)° and 50°. Find x.
Alternate interior angles are congruent: 2x + 10 = 50 → 2x = 40 → x = 20.
Same-side interior angles measure 120° and y°. Find y.
Same-side interior angles are supplementary: 120 + y = 180 → y = 60.
If corresponding angles formed by a transversal are congruent, then the two lines are:
Congruent corresponding angles prove the lines are parallel (the converse rule).
Co-interior (same-side interior) angles are (3x)° and (x + 20)°. Find x.
They are supplementary: 3x + x + 20 = 180 → 4x = 160 → x = 40.
Corresponding angles are (5x)° and (2x + 45)°. Find x.
5x = 2x + 45 → 3x = 45 → x = 15.
If two lines are cut by a transversal and same-side interior angles are supplementary, the lines are
Supplementary same-side interior angles prove the lines are parallel.
Parallel lines are cut by a transversal. Corresponding angles measure (4x)° and (x + 60)°. Find x.
Corresponding angles are equal: 4x = x + 60 → 3x = 60 → x = 20.
Alternate exterior angles measure 110° and (5x)°. Find x.
Alternate exterior angles are congruent: 5x = 110 → x = 22.
Same-side exterior angles measure x° and (x + 50)°. Find x.
Same-side exterior angles are supplementary: 2x + 50 = 180 → x = 65.
If a pair of alternate interior angles each measure 75°, then a same-side interior angle measures
Same-side interior is the supplement: 180 − 75 = 105°.
A transversal makes a 130° angle with one of two parallel lines. The same-side interior angle on the other line is
Same-side interior angles are supplementary: 180 − 130 = 50°.
Alternate interior angles measure (2x − 5)° and (x + 25)°. The measure of each angle is
2x − 5 = x + 25 → x = 30; angle = 30 + 25 = 55°.
Two parallel lines are cut by a transversal. Same-side interior angles measure (3x + 20)° and (2x − 15)°. The smaller angle measures
Supplementary: 5x + 5 = 180 → x = 35 → angles are 125° and 55°. Smaller = 55°.
Alternate interior angles measure (7x − 14)° and (4x + 22)°. Each angle measures
Equal: 7x − 14 = 4x + 22 → x = 12 → angle = 7(12) − 14 = 70°.
Corresponding angles measure (5x − 22)° and (3x + 14)°. What is the measure of the same-side interior angle paired with them?
5x − 22 = 3x + 14 → x = 18 → angle = 68°. Its same-side partner = 180 − 68 = 112°.
Alternate exterior angles measure (2x + 30)° and (4x − 10)°. Each measures
Equal: 2x + 30 = 4x − 10 → x = 20 → angle = 70°.
Lines ℓ and m are parallel. A third line is perpendicular to ℓ. The acute/right angle it makes with m is
A line perpendicular to one of two parallel lines is perpendicular to the other → 90°.
Two same-side interior angles are in the ratio 1 : 4. The smaller angle measures
x + 4x = 180 → x = 36°.
Which is an equation of the line through (2, 3) parallel to the line 3x + 2y = 8?
3x + 2y = 8 → y = −3/2 x + 4, slope −3/2. Parallel keeps the slope: y − 3 = −3/2(x − 2).
Parallel lines are cut by a transversal. One angle measures 115°. An alternate interior angle's LINEAR-PAIR partner measures
The alternate interior angle is 115°; its linear pair = 180 − 115 = 65°.
Lines ℓ and m are parallel. The two labeled angles are same-side interior angles. Find x.
Same-side interior angles are supplementary: (x + 30) + 70 = 180 → x = 80.
The two labeled angles are corresponding angles formed by a transversal crossing parallel lines. Find x.
Corresponding angles are congruent: 2x + 20 = 84 → 2x = 64 → x = 32.
Corresponding angles measure (5x + 15)° and (7x − 25)°. Each measures
5x + 15 = 7x − 25 → x = 20 → angle = 115°.
Alternate exterior angles measure (6x − 12)° and (4x + 20)°. Each measures
6x − 12 = 4x + 20 → x = 16 → angle = 84°.
Same-side interior angles measure (2x + 40)° and (3x + 30)°. The smaller one is
Sum 180: 5x + 70 = 180 → x = 22 → angles 84° and 96° → smaller 84°.
Which is an equation of the line through (1, 2) parallel to 2x − 3y = 6?
2x − 3y = 6 → y = ⅔x − 2, slope ⅔. Parallel keeps it: y − 2 = ⅔(x − 1).
Alternate interior angles measure (3x − 20)° and 70°. Find x.
Congruent: 3x − 20 = 70 → 3x = 90 → x = 30.
Two parallel lines are cut by a transversal. One angle measures 112°. A same-side EXTERIOR angle paired with it measures
Same-side exterior angles are supplementary: 180 − 112 = 68°.
A line has slope 3. Any line parallel to it has slope
Parallel lines have equal slopes.
Parallel lines are cut by a transversal. An angle of 109° and angle x are same-side interior angles. x =
Same-side interior → supplementary: 180 − 109 = 71°.
Parallel lines are cut by a transversal. An angle of 71° and angle x are same-side interior angles. x =
Same-side interior → supplementary: 180 − 71 = 109°.
A line has slope 2. Any line parallel to it has slope
Parallel lines have equal slopes.
Parallel lines are cut by a transversal. An angle of 117° and angle x are same-side interior angles. x =
Same-side interior → supplementary: 180 − 117 = 63°.
A line has slope 5. Any line parallel to it has slope
Parallel lines have equal slopes.
A line has slope -3. Any line parallel to it has slope
Parallel lines have equal slopes.
A line has slope -2. Any line parallel to it has slope
Parallel lines have equal slopes.
Parallel lines are cut by a transversal. An angle of 84° and angle x are same-side interior angles. x =
Same-side interior → supplementary: 180 − 84 = 96°.
Parallel lines are cut by a transversal. An angle of 63° and angle x are same-side interior angles. x =
Same-side interior → supplementary: 180 − 63 = 117°.
Parallel lines are cut by a transversal. An angle of 98° and angle x are same-side interior angles. x =
Same-side interior → supplementary: 180 − 98 = 82°.
A line has slope 4. Any line parallel to it has slope
Parallel lines have equal slopes.
An exterior angle of a triangle equals the sum of the two remote interior angles. If those are 50° and 70°, the exterior angle is:
Exterior Angle Theorem: 50 + 70 = 120°.
In an isosceles triangle the vertex angle is 40°. Each base angle measures:
Base angles are equal: (180 − 40) ÷ 2 = 70°.
Which set of lengths CANNOT form a triangle?
Triangle Inequality fails: 3 + 4 = 7, which is not greater than 8.
A triangle has sides 5, 12, and 13. It is a
5² + 12² = 13² (25 + 144 = 169), so it's a right triangle.
The centroid of a triangle divides each median in the ratio
The centroid divides each median 2:1 (vertex side is twice the midpoint side).
A median of a triangle is 18 long. The distance from the vertex to the centroid is
The centroid is 2/3 of the way from the vertex: (2/3)(18) = 12.
The angles of a triangle are 3x, 4x, and 5x. The largest angle is
12x = 180 → x = 15; largest = 5(15) = 75°.
An exterior angle of a triangle is 120°. If one remote interior angle is 45°, the other is
Exterior = sum of remote interiors: 120 = 45 + x → x = 75°.
Which length CANNOT be the third side of a triangle with sides 7 and 10?
Third side must be < 17 and > 3. 18 fails (7 + 10 = 17, not > 18).
In △ABC, ∠A = 50°, ∠B = 60°, ∠C = 70°. The longest side is
The longest side is opposite the largest angle (∠C = 70°), which is AB.
The acute angles of a right triangle are 2x and 3x. The larger acute angle is
2x + 3x = 90 → x = 18; larger = 3(18) = 54°.
On a median, the distance from the centroid to the midpoint is 5. The distance from the vertex to the centroid is
Centroid ratio is 2:1, so vertex-to-centroid = 2 × 5 = 10.
The angles of a triangle measure (2x + 10)°, (3x − 5)°, and (x + 25)°. The largest angle is
Sum: 6x + 30 = 180 → x = 25 → angles 60°, 70°, 50°. Largest = 70°.
An exterior angle measures (7x − 4)°; the remote interior angles are (3x + 8)° and (2x + 12)°. The exterior angle measures
7x − 4 = (3x+8) + (2x+12) → 7x − 4 = 5x + 20 → x = 12 → exterior = 80°.
In an isosceles triangle the vertex angle is (2x)° and each base angle is (4x − 10)°. The vertex angle measures
2x + 2(4x − 10) = 180 → 10x − 20 = 180 → x = 20 → vertex = 40°.
A triangle has sides 8 and 15. Which could NOT be the length of the third side?
Third side must satisfy 7 < s < 23 strictly. 7 fails because 8 + 7 = 15 is not greater than 15.
A median of a triangle is 24 units long. How far is the centroid from the MIDPOINT of the opposite side?
The centroid is 2:1 from the vertex, so the short piece = ⅓(24) = 8.
A triangle has sides 7, 24, and 25. This triangle is
7² + 24² = 49 + 576 = 625 = 25² → right triangle by the Pythagorean converse.
In △ABC, m∠A = 2·m∠B and m∠C = m∠B + 20°. Find m∠A.
2b + b + (b + 20) = 180 → 4b = 160 → b = 40 → m∠A = 80°.
An isosceles triangle has perimeter 50 and base 12. Each leg measures
Legs: (50 − 12) ÷ 2 = 19.
Find the value of x in the triangle.
Angles of a triangle sum to 180: x = 180 − 55 − 65 = 60.
A side of the triangle is extended. Find the measure of exterior angle x.
Exterior angle = sum of the two remote interior angles = 40 + 60 = 100°.
The angles of a triangle are x°, (x + 15)°, and (2x − 35)°. The triangle is
4x − 20 = 180 → x = 50 → angles 50°, 65°, 65° → two equal angles → isosceles.
An exterior angle measures (2x + 30)°; its remote interior angles are (x + 40)° and 30°. The exterior angle is
2x + 30 = x + 70 → x = 40 → exterior = 110°.
A triangle has sides 9, 40, and 41. It is
9² + 40² = 81 + 1600 = 1681 = 41² → right triangle.
MN joins the midpoints of two sides of a triangle. If MN = 3x − 2 and the parallel side BC = 5x + 6, then BC =
Midsegment = half the side: 2(3x − 2) = 5x + 6 → 6x − 4 = 5x + 6 → x = 10 → BC = 56.
A median of a triangle is 30 units. The distance from the vertex to the centroid is
Vertex-to-centroid = ⅔ of the median = 20.
An isosceles triangle has vertex angle (3x + 12)° and base angles (x + 24)° each. The vertex angle is
(3x+12) + 2(x+24) = 180 → 5x + 60 = 180 → x = 24 → vertex = 84°.
Two angles of a triangle measure 77° and 33°. The third angle measures
180 − 77 − 33 = 70°.
The remote interior angles of a triangle measure 31° and 88°. The exterior angle measures
Exterior = sum of remote interiors = 119°.
The remote interior angles of a triangle measure 48° and 73°. The exterior angle measures
Exterior = sum of remote interiors = 121°.
Two angles of a triangle measure 42° and 66°. The third angle measures
180 − 42 − 66 = 72°.
The remote interior angles of a triangle measure 40° and 70°. The exterior angle measures
Exterior = sum of remote interiors = 110°.
Two angles of a triangle measure 35° and 75°. The third angle measures
180 − 35 − 75 = 70°.
The remote interior angles of a triangle measure 55° and 45°. The exterior angle measures
Exterior = sum of remote interiors = 100°.
Two angles of a triangle measure 51° and 49°. The third angle measures
180 − 51 − 49 = 80°.
The remote interior angles of a triangle measure 62° and 38°. The exterior angle measures
Exterior = sum of remote interiors = 100°.
The remote interior angles of a triangle measure 66° and 52°. The exterior angle measures
Exterior = sum of remote interiors = 118°.
Two angles of a triangle measure 28° and 94°. The third angle measures
180 − 28 − 94 = 58°.
Two angles of a triangle measure 63° and 58°. The third angle measures
180 − 63 − 58 = 59°.
In SAS, the angle used must be:
SAS requires the angle BETWEEN the two given sides (the included angle).
CPCTC can be used:
CPCTC (corresponding parts...) is only used AFTER you prove the triangles congruent.
If △ABC ≅ △DEF, then angle B corresponds to:
Matching the naming order A↔D, B↔E, C↔F. So ∠B ↔ ∠E.
Two angles and the side between them are congruent. This is:
ASA = two angles with the INCLUDED side between them.
Which pair of given parts would let you use AAS?
AAS = two angles and a side that is NOT between them.
Vertical angles in two triangles can be used in a proof because they are
Vertical angles are always congruent — useful as an angle pair in proofs.
To prove △MIE ≅ △LSE using a pair of vertical angles plus two angle pairs, you would cite
Two angles (including the vertical-angle pair) plus a side give ASA or AAS.
Two angles and the side between them are congruent. This proves congruence by
ASA = two angles with the included side.
In △ABC ≅ △DEF, angle B corresponds to
Matching order A↔D, B↔E, C↔F → ∠B ↔ ∠E.
If △ABC ≅ △DEF and m∠A = 50°, then m∠D =
Corresponding angles of congruent triangles are equal: ∠D = 50°.
If △ABC ≅ △DEF and EF = 9, then BC =
Corresponding sides are congruent: BC ↔ EF = 9.
Two sides and the angle BETWEEN them are congruent. This is
SAS = two sides with the included angle.
Given AB ≅ DE and ∠A ≅ ∠D, which additional congruence lets you conclude △ABC ≅ △DEF by ASA?
For ASA the given side must be INCLUDED between the two angles: AB lies between ∠A and ∠B, so you need ∠B ≅ ∠E.
△ABC ≅ △XYZ, AB = 3x + 7 and XY = 5x − 9. The length of AB is
Corresponding sides equal: 3x + 7 = 5x − 9 → x = 8 → AB = 31.
Triangles ABC and ADE share ∠A, with AB ≅ AD and AC ≅ AE. The triangles are congruent by
Two pairs of sides with the shared included angle ∠A → SAS.
In right triangles ABC and DEF, ∠C and ∠F are right angles, AC ≅ DF, and hypotenuses AB ≅ DE. The triangles are congruent by
Right angle + congruent hypotenuse + congruent leg = HL.
Which piece of information is NOT sufficient (with nothing else) to help prove two triangles congruent?
Equal areas say nothing about shape — many non-congruent triangles share an area.
After proving △ABC ≅ △DEF, the statement BC ≅ EF is justified by
Once the triangles are congruent, corresponding parts are congruent (CPCTC).
Segments AC and BD bisect each other at M. △AMB ≅ △CMD by
Bisecting gives AM ≅ MC and BM ≅ MD; vertical angles ∠AMB ≅ ∠CMD are included → SAS.
△ABC ≅ △DEF, m∠B = (4x + 6)° and m∠E = (6x − 18)°. Find m∠B.
4x + 6 = 6x − 18 → x = 12 → m∠B = 4(12) + 6 = 54°.
Segments AC and BD intersect at M, with AM ≅ MC (single ticks) and BM ≅ MD (double ticks). △AMB ≅ △CMD by
Two pairs of congruent sides plus the included VERTICAL angles at M → SAS.
Two right triangles have congruent hypotenuses (single ticks) and one pair of congruent legs (double ticks). They are congruent by
Right angle + hypotenuse + leg is the HL theorem (valid for right triangles only).
Given ∠A ≅ ∠D, ∠B ≅ ∠E, and AB ≅ DE, the triangles are congruent by
AB is the side INCLUDED between ∠A and ∠B → ASA.
Given AB ≅ DE, BC ≅ EF, and ∠B ≅ ∠E, the triangles are congruent by
∠B is included between sides AB and BC → SAS.
A sequence of rigid motions maps △ABC onto △DEF. The triangles must be congruent because rigid motions preserve
Rigid motions preserve distance and angle measure, so all corresponding parts match.
△ABC ≅ △DEF with AB = 2x + 9 and DE = 4x − 13. AB =
2x + 9 = 4x − 13 → x = 11 → AB = 31.
Two triangles share vertical angles at M, and one pair of sides AM ≅ MC is marked. For SAS you also need
SAS needs the second pair of sides that FORM the vertical angle: BM ≅ MD.
After a reflection then a translation, △PQR lands exactly on △P'Q'R'. Which statement must be true?
Reflections and translations are rigid motions → the image is congruent (orientation flipped by the reflection).
△ABC ≅ △DEF. AB = 5x + 4 and DE = 34. Then x =
Corresponding sides equal: 5x + 4 = 34 → x = 6.
△PQR ≅ △XYZ and m∠Q = 71°. Then m∠Y =
Corresponding angles of congruent triangles are equal.
△ABC ≅ △DEF. AB = 4x + 11 and DE = 43. Then x =
Corresponding sides equal: 4x + 11 = 43 → x = 8.
△PQR ≅ △XYZ and m∠Q = 58°. Then m∠Y =
Corresponding angles of congruent triangles are equal.
△ABC ≅ △DEF. AB = 2x + 9 and DE = 33. Then x =
Corresponding sides equal: 2x + 9 = 33 → x = 12.
△PQR ≅ △XYZ and m∠Q = 47°. Then m∠Y =
Corresponding angles of congruent triangles are equal.
△ABC ≅ △DEF. AB = 3x + 7 and DE = 34. Then x =
Corresponding sides equal: 3x + 7 = 34 → x = 9.
△PQR ≅ △XYZ and m∠Q = 34°. Then m∠Y =
Corresponding angles of congruent triangles are equal.
A figure is dilated by a scale factor of 3. Its area is multiplied by:
Area scales by k²: 3² = 9.
A solid is enlarged by scale factor 2. Its volume is multiplied by:
Volume scales by k³: 2³ = 8.
The altitude to the hypotenuse splits it into pieces of 4 and 9. The altitude length is:
Geometric mean: altitude = √(4·9) = √36 = 6.
Two similar triangles have a side ratio of 2 : 5. The ratio of their areas is
Area ratio = (side ratio)² = 2² : 5² = 4 : 25.
In △ABC, DE ∥ AC with D on AB and E on CB. If BD = 6, DA = 4, and BE = 9, then EC =
Side-Splitter: BD/DA = BE/EC → 6/4 = 9/EC → EC = 6.
Two similar triangles have a side ratio of 3:4. If the smaller perimeter is 15, the larger perimeter is
Perimeter ratio = side ratio: 15/x = 3/4 → x = 20.
A solid is dilated by scale factor ½. Its volume is multiplied by
Volume scales by k³: (½)³ = 1/8.
In △ABC, DE ∥ AC with BD = 8, DA = 4, BE = 10. Then EC =
Side-Splitter: BD/DA = BE/EC → 8/4 = 10/EC → EC = 5.
The geometric mean (altitude) for hypotenuse segments 9 and 4 is
Altitude = √(9·4) = √36 = 6.
Two similar polygons have a scale factor of 5:2. The ratio of their areas is
Area ratio = (5:2)² = 25:4.
△ABC ∼ △DEF with ratio 2:3. If AB = 10, then DE =
10/DE = 2/3 → 2·DE = 30 → DE = 15.
In similar figures, corresponding angles are
Similar figures have congruent (equal) corresponding angles.
△ABC ∼ △DEF with AB = 8 and DE = 12. If the perimeter of △ABC is 30, the perimeter of △DEF is
Scale factor 12/8 = 3/2. Perimeter scales by k: 30 × 3/2 = 45.
Two similar triangles have areas 36 and 81. If a side of the smaller is 10, the corresponding side of the larger is
Area ratio 36:81 = 4:9 → side ratio 2:3 → 10 × 3/2 = 15.
The altitude to the hypotenuse measures 12 and one hypotenuse segment measures 9. The other segment measures
altitude² = (seg₁)(seg₂): 144 = 9x → x = 16.
DE ∥ AC in △ABC. BD = x, DA = x − 4, BE = 15, EC = 10. Find x.
Side-Splitter: x/(x−4) = 15/10 → 10x = 15x − 60 → x = 12.
In a right triangle, a leg measures 10 and the hypotenuse segment adjacent to that leg measures 5. The whole hypotenuse measures
leg² = (adjacent segment)(whole hypotenuse): 100 = 5h → h = 20.
Two similar solids have volumes in the ratio 8 : 27. Their surface areas are in the ratio
Volume ratio 8:27 → side ratio 2:3 → area ratio 2²:3² = 4:9.
DE ∥ AC creates △BDE ∼ △BAC. If BD = 6, BA = 10, and DE = 9, then AC =
BD/BA = DE/AC → 6/10 = 9/AC → AC = 15.
A dilation with scale factor 2.5 maps segment PQ of length 6 onto P'Q'. The length of P'Q' is
Lengths multiply by k: 6 × 2.5 = 15.
In △ABC, DE ∥ AC. BD = 4, DA = 2, BE = 6, EC = x. Find x.
Side-Splitter: BD/DA = BE/EC → 4/2 = 6/x → x = 3.
The two right triangles are similar, with corresponding sides as labeled. Find x.
6/9 = 8/x → 6x = 72 → x = 12.
Two similar triangles have areas in the ratio 9 : 25. If the smaller perimeter is 27, the larger perimeter is
Side ratio = √(9:25) = 3:5 → perimeter 27 × 5/3 = 45.
The altitude to the hypotenuse splits it into segments of 8 and 18. The altitude measures
h = √(8·18) = √144 = 12.
DE ∥ AC with BD = 5, DA = 7, BE = 10. Then EC =
5/7 = 10/EC → 5·EC = 70 → EC = 14.
Two similar triangles have shortest sides 6 and 15. If the longer triangle's longest side is 20, the smaller triangle's longest side is
k = 15/6 = 2.5 → 20 ÷ 2.5 = 8.
Two similar solids have volumes in the ratio 27 : 64. Their surface areas are in the ratio
Side ratio = ∛(27:64) = 3:4 → area ratio = 9:16.
In a right triangle, a leg measures 12 and the whole hypotenuse measures 16. The hypotenuse segment adjacent to that leg is
leg² = (adjacent segment)(hypotenuse): 144 = 16s → s = 9.
A figure is dilated by scale factor 5. Its area is multiplied by
Area scales by k² = 25.
△ABC ∼ △DEF. AB = 4, DE = 10, BC = 6. Then EF =
4/10 = 6/EF → EF = 15.
△ABC ∼ △DEF. AB = 8, DE = 12, BC = 10. Then EF =
8/12 = 10/EF → EF = 15.
△ABC ∼ △DEF. AB = 6, DE = 8, BC = 9. Then EF =
6/8 = 9/EF → EF = 12.
△ABC ∼ △DEF. AB = 3, DE = 9, BC = 5. Then EF =
3/9 = 5/EF → EF = 15.
A figure is dilated by scale factor 6. Its area is multiplied by
Area scales by k² = 36.
△ABC ∼ △DEF. AB = 5, DE = 10, BC = 7. Then EF =
5/10 = 7/EF → EF = 14.
A figure is dilated by scale factor 3. Its area is multiplied by
Area scales by k² = 9.
△ABC ∼ △DEF. AB = 4, DE = 6, BC = 10. Then EF =
4/6 = 10/EF → EF = 15.
A figure is dilated by scale factor 4. Its area is multiplied by
Area scales by k² = 16.
A figure is dilated by scale factor 10. Its area is multiplied by
Area scales by k² = 100.
A right triangle has a hypotenuse of 10 and an angle of 30°. The side OPPOSITE the 30° angle is:
sin30° = opp/10 → opp = 10 × 0.5 = 5.
sin(30°) is equal to:
Co-function: sin(x) = cos(90 − x), so sin30° = cos60°.
In a 45-45-90 triangle with leg length 5, the hypotenuse is:
In a 45-45-90 triangle, hypotenuse = leg · √2 = 5√2.
In a 45-45-90 triangle, the hypotenuse is 10. Each leg is
hypotenuse = leg·√2 → leg = 10/√2 = 5√2.
cos(40°) is equal to
Co-function: cos(x) = sin(90 − x), so cos40° = sin50°.
If sin(2x)° = cos(40)°, then x =
Cofunctions: 2x + 40 = 90 → 2x = 50 → x = 25.
In a right triangle, an acute angle is 40° and the adjacent leg is 10. The opposite leg is about
tan(40°) = opp/10 → opp = 10·tan40° ≈ 8.4.
A triangle has sides 10 and 12 with a 30° included angle. Its area is
Area = ½·a·b·sin(C) = ½·10·12·sin30° = ½·120·0.5 = 30.
In a 30-60-90 triangle the hypotenuse is 12. The longer leg is
Short leg = ½·12 = 6; longer leg = 6√3 (ratio 1 : √3 : 2).
Which expression equals cos(40°)?
Cofunction: cos(x) = sin(90 − x), so cos40° = sin50°.
In a 30-60-90 triangle, the shorter leg is 5. The hypotenuse is
Hypotenuse = 2 × shorter leg = 10.
A right triangle has the side opposite θ = 3 and the adjacent side = 4. Then θ ≈
tan θ = 3/4 → θ = tan⁻¹(0.75) ≈ 37°.
A 20-foot ladder makes a 65° angle with the ground. How high up the wall does it reach, to the nearest tenth?
Height is opposite the 65° angle: h = 20·sin65° ≈ 20(0.9063) ≈ 18.1 ft.
From a point 120 ft from a building's base, the angle of elevation to the top is 32°. The building's height, to the nearest foot, is
tan32° = h/120 → h = 120·tan32° ≈ 75 ft.
A right triangle has the side opposite θ = 7 and the side adjacent = 10. Find θ to the nearest degree.
θ = tan⁻¹(7/10) = tan⁻¹(0.7) ≈ 35°.
In a 45-45-90 triangle the hypotenuse measures 14. Each leg measures
leg = hyp ÷ √2 = 14/√2 = 7√2.
In a 30-60-90 triangle the LONGER leg measures 9. The hypotenuse measures
Short leg = 9/√3 = 3√3; hypotenuse = 2(3√3) = 6√3.
If sin(3x + 10)° = cos(2x + 20)°, then x =
Cofunctions sum to 90: (3x+10) + (2x+20) = 90 → 5x = 60 → x = 12.
A right triangle has hypotenuse 25 and one leg 15. The sine of the angle opposite the OTHER leg is
Other leg = √(625−225) = 20. sin = opposite/hypotenuse = 20/25 = 4/5.
From the top of a 90-ft lighthouse, the angle of depression to a boat is 28°. The horizontal distance to the boat, to the nearest foot, is
tan28° = 90/d → d = 90/tan28° ≈ 90/0.5317 ≈ 169 ft.
Find the missing leg x of the right triangle.
x² + 5² = 13² → x² = 169 − 25 = 144 → x = 12. (5-12-13 triple.)
In the right triangle, the hypotenuse is 20 and the marked angle is 35°. Find x to the nearest tenth.
x is opposite the 35° angle: x = 20·sin35° ≈ 20(0.5736) ≈ 11.5.
If sin(4x − 2)° = cos(3x + 8)°, then x =
Cofunctions: (4x−2)+(3x+8) = 90 → 7x + 6 = 90 → x = 12.
A kite string is 100 m long and makes a 42° angle with the ground. The kite's height, to the nearest tenth, is
h = 100·sin42° ≈ 100(0.6691) ≈ 66.9 m.
A wheelchair ramp rises 3 ft over a horizontal run of 20 ft. The angle it makes with the ground, to the nearest tenth of a degree, is
θ = tan⁻¹(3/20) = tan⁻¹(0.15) ≈ 8.5°.
In a 30-60-90 triangle the hypotenuse is 18. The longer leg measures
Short leg = 9; longer leg = 9√3.
A right triangle has a leg of 9 and hypotenuse 15. The cosine of the angle opposite the 9-side is
Other leg = 12. The angle opposite 9 has adjacent 12 → cos = 12/15 = 4/5.
From the top of a 150-ft tower, the angle of depression to a car is 22°. The horizontal distance to the car, to the nearest foot, is
d = 150/tan22° ≈ 150/0.4040 ≈ 371 ft.
A right triangle has legs 20 and 21. The hypotenuse is
√(20²+21²) = 29.
In a right triangle the side opposite θ is 11 and the adjacent side is 6. θ to the nearest degree is
θ = tan⁻¹(11/6) ≈ 61°.
A right triangle has legs 3 and 4. The hypotenuse is
√(3²+4²) = 5.
A right triangle has hypotenuse 13 and one leg 5. The other leg is
√(13²−5²) = 12.
A right triangle has hypotenuse 15 and one leg 9. The other leg is
√(15²−9²) = 12.
A right triangle has legs 5 and 12. The hypotenuse is
√(5²+12²) = 13.
A right triangle has legs 8 and 15. The hypotenuse is
√(8²+15²) = 17.
A right triangle has legs 7 and 24. The hypotenuse is
√(7²+24²) = 25.
In a right triangle the side opposite θ is 7 and the adjacent side is 10. θ to the nearest degree is
θ = tan⁻¹(7/10) ≈ 35°.
A right triangle has hypotenuse 17 and one leg 8. The other leg is
√(17²−8²) = 15.
In a right triangle the side opposite θ is 9 and the adjacent side is 12. θ to the nearest degree is
θ = tan⁻¹(9/12) ≈ 37°.
A right triangle has hypotenuse 25 and one leg 7. The other leg is
√(25²−7²) = 24.
In a right triangle the side opposite θ is 3 and the adjacent side is 8. θ to the nearest degree is
θ = tan⁻¹(3/8) ≈ 21°.
A right triangle has hypotenuse 29 and one leg 20. The other leg is
√(29²−20²) = 21.
A right triangle has legs 9 and 12. The hypotenuse is
√(9²+12²) = 15.
A right triangle has hypotenuse 5 and one leg 3. The other leg is
√(5²−3²) = 4.
A right triangle has legs 6 and 8. The hypotenuse is
√(6²+8²) = 10.
In a right triangle the side opposite θ is 8 and the adjacent side is 5. θ to the nearest degree is
θ = tan⁻¹(8/5) ≈ 58°.
A right triangle has hypotenuse 10 and one leg 6. The other leg is
√(10²−6²) = 8.
In a right triangle the side opposite θ is 5 and the adjacent side is 12. θ to the nearest degree is
θ = tan⁻¹(5/12) ≈ 23°.
The sum of the interior angles of a pentagon (5 sides) is:
(n − 2)·180 = (5 − 2)·180 = 540°.
The sum of the exterior angles of ANY polygon is:
Exterior angles of any polygon always total 360°.
Each interior angle of a regular hexagon (6 sides) measures:
(6−2)·180 ÷ 6 = 720 ÷ 6 = 120°.
Which quadrilateral always has perpendicular diagonals?
A rhombus has diagonals that are perpendicular (and bisect the angles).
A regular polygon has each exterior angle equal to 40°. How many sides does it have?
Number of sides = 360 ÷ exterior angle = 360 ÷ 40 = 9.
The sum of the interior angles of a decagon (10 sides) is
(10 − 2)·180 = 8·180 = 1440°.
Which is always true of a rectangle but NOT always of a rhombus?
Rectangles have congruent diagonals; rhombus diagonals are usually unequal.
A trapezoid has bases of length 8 and 14. The length of its midsegment (median) is
Midsegment = ½(b₁ + b₂) = ½(8 + 14) = 11.
The sum of the interior angles of a heptagon (7 sides) is
(7 − 2)·180 = 900°.
A regular polygon has each exterior angle equal to 36°. It has
360 ÷ 36 = 10 sides.
Each interior angle of a regular pentagon measures
(5−2)·180 ÷ 5 = 540 ÷ 5 = 108°.
Consecutive angles of a parallelogram are always
Consecutive angles of a parallelogram are supplementary.
Each interior angle of a regular polygon measures 156°. The number of sides is
Exterior = 180 − 156 = 24° → n = 360/24 = 15.
In parallelogram ABCD, m∠A = (3x + 12)° and m∠C = (5x − 26)°. Find m∠A.
Opposite angles equal: 3x + 12 = 5x − 26 → x = 19 → m∠A = 69°.
Consecutive angles of a parallelogram measure (2x + 40)° and (3x − 10)°. The larger angle measures
Supplementary: 5x + 30 = 180 → x = 30 → angles 100° and 80°. Larger = 100°.
The diagonals of a rhombus measure 12 and 16. The length of one side of the rhombus is
Diagonals bisect at right angles: side = √(6² + 8²) = 10.
In an isosceles trapezoid, a lower base angle measures 70°. An upper base angle measures
Same-side angles between the parallel bases are supplementary: 180 − 70 = 110°.
The interior angles of a polygon sum to 1620°. The polygon has how many sides?
(n − 2)·180 = 1620 → n − 2 = 9 → n = 11.
In rectangle ABCD, diagonal AC = 3x + 8 and diagonal BD = 5x − 12. The length of each diagonal is
Rectangle diagonals are congruent: 3x + 8 = 5x − 12 → x = 10 → AC = 38.
A trapezoid's midsegment measures 17 and one base measures 12. The other base measures
17 = ½(12 + b) → 34 = 12 + b → b = 22.
In the parallelogram, find x.
Consecutive angles of a parallelogram are supplementary: x = 180 − 65 = 115.
The figure is a regular hexagon. Find the measure of interior angle x.
Each interior angle of a regular hexagon = (6−2)·180 ÷ 6 = 120°.
Each interior angle of a regular 20-gon measures
(20−2)·180/20 = 3240/20 = 162°.
Parallelogram diagonals meet at E. If AE = 3x − 4 and EC = x + 12, diagonal AC =
Diagonals bisect: 3x − 4 = x + 12 → x = 8 → AE = 20 → AC = 40.
A rhombus has perimeter 52 and one diagonal of length 24. The other diagonal measures
Side = 13; half-diagonals 12 and √(13²−12²) = 5 → other diagonal = 10.
In an isosceles trapezoid, the diagonals measure (5x − 9) and (3x + 7). Each diagonal is
Diagonals congruent: 5x − 9 = 3x + 7 → x = 8 → 31.
Each exterior angle of a regular polygon measures 18°. The polygon has
n = 360/18 = 20 sides.
A square has a diagonal of length 8√2. Its area is
Diagonal = s√2 → s = 8 → area = 64.
Each exterior angle of a regular polygon measures 40°. The polygon has
n = 360/40 = 9.
The interior angles of a regular 6-gon each measure
(n−2)·180/n = 120°.
The interior angles of a regular 5-gon each measure
(n−2)·180/n = 108°.
Each exterior angle of a regular polygon measures 30°. The polygon has
n = 360/30 = 12.
The interior angles of a regular 12-gon each measure
(n−2)·180/n = 150°.
Each exterior angle of a regular polygon measures 72°. The polygon has
n = 360/72 = 5.
The interior angles of a regular 9-gon each measure
(n−2)·180/n = 140°.
Each exterior angle of a regular polygon measures 60°. The polygon has
n = 360/60 = 6.
Each exterior angle of a regular polygon measures 36°. The polygon has
n = 360/36 = 10.
The interior angles of a regular 10-gon each measure
(n−2)·180/n = 144°.
Each exterior angle of a regular polygon measures 45°. The polygon has
n = 360/45 = 8.
The equation (x − 2)² + (y + 3)² = 16 describes a circle with center and radius:
Center is (h, k) = (2, −3) (signs flip), and r = √16 = 4.
Two chords intersect inside a circle, cutting arcs of 60° and 80°. The angle formed is:
Inside angle = ½(sum of arcs) = ½(60 + 80) = 70°.
A 90° central angle in a circle of radius 6 cuts off an arc of length:
Arc length = (90/360)·2π(6) = ¼·12π = 3π.
A tangent and a radius drawn to the point of tangency form an angle of
A tangent is perpendicular to the radius at the point of tangency → 90°.
The circle (x + 1)² + (y − 5)² = 9 has center and radius
Center (h, k) = (−1, 5) (signs flip); r = √9 = 3.
A circle has radius 9. The length of an arc with a central angle of 80° is
(80/360)·2π(9) = (2/9)(18π) = 4π.
The center of the circle x² + y² + 6x − 4y − 12 = 0 is
Complete the square: (x+3)² + (y−2)² = 25 → center (−3, 2), radius 5.
A quadrilateral is inscribed in a circle. If one angle is 95°, its opposite angle is
Opposite angles of a cyclic quadrilateral are supplementary: 180 − 95 = 85°.
From an external point, a tangent of length 6 and a secant are drawn. If the external part of the secant is 4, the whole secant length is
Tangent² = (whole)(external): 6² = 4·whole → whole = 36/4 = 9.
Two secants from an external point have (whole)(external) products. If one secant gives 8 and 3, and the other has whole length 6 and external part x, then x =
(8)(3) = (6)(x) → 24 = 6x → x = 4.
The circle (x − 5)² + (y + 2)² = 49 has center and radius
Center (5, −2); r = √49 = 7.
In a circle of radius 12, an arc with a 30° central angle has length
(30/360)·2π(12) = (1/12)(24π) = 2π.
Two chords intersect inside a circle. One chord is split into 6 and 8; the other into 4 and x. Find x.
(6)(8) = (4)(x) → 48 = 4x → x = 12.
An inscribed angle measures 48°. A CENTRAL angle intercepting the same arc measures
The arc = 2(48) = 96°, and the central angle equals its arc → 96°.
A sector of a circle with radius 9 has a central angle of 80°. The area of the sector is
(80/360)·π(9²) = (2/9)(81π) = 18π.
A tangent of length 12 and a secant are drawn from the same external point. The secant's external segment is 8. The part of the secant INSIDE the circle measures
tangent² = (whole)(external): 144 = 8w → w = 18 → inside part = 18 − 8 = 10.
The circle x² + y² − 8x + 4y + 4 = 0 has radius
(x−4)² + (y+2)² = −4 + 16 + 4 = 16 → r = 4.
Two tangents from an external point form a 40° angle. If the NEAR arc measures 140°, the FAR arc measures
The two arcs total 360°: far = 360 − 140 = 220°. Check: ½(220 − 140) = 40° ✓.
A quadrilateral is inscribed in a circle. If ∠A = (2x + 10)° and its opposite angle ∠C = (3x + 20)°, find m∠A.
Opposite angles are supplementary: 5x + 30 = 180 → x = 30 → ∠A = 70°.
A chord of length 24 is drawn in a circle of radius 13. The distance from the center to the chord is
Half-chord = 12; distance = √(13² − 12²) = √25 = 5.
The inscribed angle x intercepts a 100° arc. Find x.
Inscribed angle = ½ its intercepted arc = ½(100) = 50°.
Two chords intersect inside the circle with segments as labeled. Find x.
(3)(8) = (4)(x) → 24 = 4x → x = 6.
A circle has radius 9. An arc intercepted by a 120° central angle has length
(120/360)·2π(9) = ⅓·18π = 6π.
A tangent and a chord meet at the point of tangency forming a 62° angle. The intercepted arc measures
Tangent-chord angle = ½ the arc → arc = 2(62) = 124°.
Which is the equation of a circle with center (−4, 3) and radius 6?
(x−h)²+(y−k)²=r² with h=−4, k=3, r²=36.
The circle x² + y² − 10x + 6y + 18 = 0 has center and radius
(x−5)² + (y+3)² = −18+25+9 = 16 → center (5,−3), r = 4.
Two secants from an external point intercept arcs of 200° and 80°. The angle between the secants is
½(200 − 80) = 60°.
A chord of length 30 is 8 units from the center of a circle. The radius is
r = √(15² + 8²) = √289 = 17.
An inscribed angle intercepts an arc of 126°. The angle measures
Inscribed = ½ arc = 63°.
An inscribed angle intercepts an arc of 88°. The angle measures
Inscribed = ½ arc = 44°.
An inscribed angle intercepts an arc of 148°. The angle measures
Inscribed = ½ arc = 74°.
The circle (x − 2)² + (y + 3)² = 16 has radius
r = √16 = 4.
An inscribed angle intercepts an arc of 104°. The angle measures
Inscribed = ½ arc = 52°.
An inscribed angle intercepts an arc of 72°. The angle measures
Inscribed = ½ arc = 36°.
The circle (x + 5)² + (y + 2)² = 49 has radius
r = √49 = 7.
The circle (x − 0)² + (y − 6)² = 9 has radius
r = √9 = 3.
The circle (x − 4)² + (y + 1)² = 81 has radius
r = √81 = 9.
The circle (x + 1)² + (y − 5)² = 36 has radius
r = √36 = 6.
An inscribed angle intercepts an arc of 56°. The angle measures
Inscribed = ½ arc = 28°.
The midpoint of the segment from (2, 4) to (6, 8) is:
Average the coordinates: ((2+6)/2, (4+8)/2) = (4, 6).
The slope of the line through (1, 2) and (3, 8) is:
m = (8 − 2)/(3 − 1) = 6/2 = 3.
A line has slope 2. A line PERPENDICULAR to it has slope:
Perpendicular slope is the negative reciprocal of 2, which is −1/2.
The distance between (1, 1) and (4, 5) is:
d = √(3² + 4²) = √25 = 5.
The midpoint of (−2, 3) and (4, 7) is:
((−2+4)/2, (3+7)/2) = (1, 5).
A line perpendicular to a line with slope −2/3 has slope
Negative reciprocal of −2/3 is +3/2.
The midpoint of A(−4, 2) and B(6, −8) is
((−4+6)/2, (2−8)/2) = (1, −3).
Point P divides the segment from A(0, 0) to B(10, 5) in the ratio 3:2. P is
Move 3/5 of the way: (0.6·10, 0.6·5) = (6, 3).
A line perpendicular to a line of slope 5 has slope
Negative reciprocal of 5 is −1/5.
Which is the equation of the line through (2, 3) perpendicular to y = −2x + 1?
Perpendicular slope = ½ (negative reciprocal of −2); point-slope through (2,3): y − 3 = ½(x − 2).
The slope of the line through (2, 1) and (5, 10) is
(10 − 1)/(5 − 2) = 9/3 = 3.
A line perpendicular to a line with slope 1/4 has slope
Negative reciprocal of 1/4 is −4.
Point P divides the segment from A(−4, 2) to B(6, 7) in the ratio 2 : 3. The coordinates of P are
Move 2/5 of the way: x = −4 + 0.4(10) = 0; y = 2 + 0.4(5) = 4 → (0, 4).
Which is an equation of the perpendicular bisector of the segment with endpoints (2, 4) and (6, 8)?
Midpoint (4, 6); segment slope = 1 → perpendicular slope = −1: y − 6 = −(x − 4).
A triangle has vertices (0, 0), (4, 0), and (2, 6). This triangle is
Sides: 4, √(4+36) = √40, √40. Two equal sides → isosceles.
Which is an equation of the line through (−2, 5) parallel to y = −3x + 1?
Keep slope −3: y − 5 = −3(x + 2) → y = −3x − 1.
The distance between (−3, 4) and (5, −2) is
√(8² + (−6)²) = √100 = 10.
To prove a quadrilateral is a parallelogram using slopes, you must show
Equal slopes on both pairs of opposite sides prove both pairs parallel → parallelogram.
A circle has center (3, −1) and passes through (7, 2). Its equation is
r = √(4² + 3²) = 5 → (x−3)² + (y+1)² = 25.
M(1, 2) is the midpoint of AB with A(−3, 5). The coordinates of B are
B = (2·1 − (−3), 2·2 − 5) = (5, −1).
Points A(1, 1) and B(7, 9) are graphed. What is the length of segment AB?
d = √((7−1)² + (9−1)²) = √(36 + 64) = √100 = 10.
A line passes through (0, 1) and (4, 4). What is its slope?
m = (4 − 1)/(4 − 0) = 3/4.
Point P divides the segment from R(−3, 5) to Z(9, −3) in the ratio 3 : 1. P is
¾ of the way: x = −3 + ¾(12) = 6; y = 5 + ¾(−8) = −1 → (6, −1).
Which is an equation of the line through (4, −1) perpendicular to y = ½x + 3?
Perpendicular slope = −2: y + 1 = −2(x − 4).
To prove a quadrilateral is a trapezoid using coordinates, it is sufficient to show
A trapezoid needs one pair of parallel sides — shown by equal slopes (and the other pair not parallel).
The distance from (−2, −1) to (10, 4) is
√(12² + 5²) = √169 = 13.
The line y = ½x + 2 is dilated by scale factor 4 centered at the origin. The image is
Slope unchanged; the y-intercept scales: 2 × 4 = 8 → y = ½x + 8.
The midpoint of the segment joining (−2, 7) and (6, −3) is
((−2+6)/2, (7−3)/2) = (2, 2).
The distance between (-3, 2) and (3, 10) is
√(6² + 8²) = 10.
The midpoint of (5, 0) and (9, 8) is
Average the x's and the y's.
The midpoint of (0, -5) and (6, 1) is
Average the x's and the y's.
The midpoint of (-2, 3) and (4, 7) is
Average the x's and the y's.
The distance between (1, -2) and (9, 4) is
√(8² + 6²) = 10.
The distance between (0, 3) and (8, 9) is
√(8² + 6²) = 10.
The distance between (0, 0) and (6, 8) is
√(6² + 8²) = 10.
The midpoint of (3, 3) and (9, 11) is
Average the x's and the y's.
The distance between (2, 1) and (7, 13) is
√(5² + 12²) = 13.
The midpoint of (2, 4) and (6, 8) is
Average the x's and the y's.
The distance between (-2, -1) and (4, 7) is
√(6² + 8²) = 10.
The midpoint of (-4, 2) and (2, -6) is
Average the x's and the y's.
Rotating (2, 5) 180° about the origin gives:
180° rotation: (x, y) → (−x, −y) = (−2, −5).
Rotating (3, 1) 90° counterclockwise about the origin gives:
90° CCW: (x, y) → (−y, x) = (−1, 3).
Reflecting (2, 7) over the line y = x gives:
Reflection over y = x swaps coordinates: (x, y) → (y, x) = (7, 2).
A rigid motion preserves all of the following EXCEPT:
Rigid motions preserve distance, angle, and area — but change the figure's position.
Reflecting (−2, 7) over the line y = x gives
Reflection over y = x swaps coordinates: (−2, 7) → (7, −2).
A translation maps (1, 1) to (4, −3). The rule is
x: 1→4 is +3; y: 1→−3 is −4. Rule (x+3, y−4).
What is the smallest angle of rotation that maps a regular octagon onto itself?
360 ÷ 8 = 45°.
A regular pentagon carries onto itself after a rotation of
360 ÷ 5 = 72°.
The line y = 3x is dilated by scale factor 2 centered at the origin. The image is
The line passes through the center of dilation, so it maps onto itself: y = 3x.
Reflecting (3, −5) over the line y = x gives
Reflection over y = x swaps coordinates: (3, −5) → (−5, 3).
Under the translation (x, y) → (x − 5, y + 2), the point (3, 3) maps to
(3 − 5, 3 + 2) = (−2, 5).
Rotating (5, 2) 90° counterclockwise about the origin gives
90° CCW: (x, y) → (−y, x) = (−2, 5).
The point (2, 3) is rotated 90° counterclockwise about the origin, then reflected over the x-axis. The final image is
R90CCW: (2,3) → (−3, 2). Reflect over x-axis: (−3, 2) → (−3, −2).
The point (1, 4) is translated by (x + 3, y − 2), then rotated 180° about the origin. The final image is
Translate: (4, 2). Rotate 180°: (−4, −2).
The point (3, 1) is dilated by scale factor 2 about the origin, then translated by (x, y − 3). The final image is
Dilate: (6, 2). Translate down 3: (6, −1).
The point (4, 7) is reflected over the line y = x, then over the y-axis. The final image is
Over y = x: (7, 4). Over the y-axis: (−7, 4).
Rotating (−2, 5) by 270° counterclockwise about the origin gives
270° CCW: (x, y) → (y, −x) = (5, −(−2)) = (5, 2).
A dilation with scale factor ½ centered at the origin is applied to a segment of length 10. The image segment has length
Lengths multiply by k = ½: 10 × ½ = 5.
A glide reflection is the composition of a
A glide reflection = translation followed by (or with) a reflection over a parallel line.
Which transformation REVERSES the orientation of a figure's vertices?
Reflections flip orientation (clockwise labels become counterclockwise). Translations, rotations, dilations preserve it.
△A'B'C' is the mirror image of △ABC across the vertical axis shown. Which single transformation maps △ABC onto △A'B'C'?
The image is flipped across the vertical (y) axis — a reflection over the y-axis.
Point P(3, 2) maps to P'(−2, 3). Which transformation occurred?
90° CCW rule: (x, y) → (−y, x): (3, 2) → (−2, 3) ✓.
The smallest rotation that carries a regular decagon onto itself is
360/10 = 36°.
The rule (x, y) → (y, −x) represents a rotation of
(y, −x) is 90° clockwise (equivalently 270° CCW).
P(5, −1) is reflected over the y-axis, then translated up 2. The final image is
Reflect: (−5, −1). Up 2: (−5, 1).
Rotating (2, 3) 90° clockwise about the origin gives
90° CW: (x, y) → (y, −x) = (3, −2).
Which transformation preserves distance but NOT orientation?
A reflection is rigid (distance-preserving) but flips orientation.
The line y = 2x + 4 is dilated by scale factor 3 centered at the origin. The image is
Slope stays 2; intercept triples: y = 2x + 12.
Reflecting (3, 2) over the line y = x gives
Over y = x: swap the coordinates.
Rotating (1, 7) 90° counterclockwise about the origin gives
90° CCW: (x, y) → (−y, x).
Reflecting (6, -4) over the line y = x gives
Over y = x: swap the coordinates.
Reflecting (-3, -2) over the line y = x gives
Over y = x: swap the coordinates.
Reflecting (5, 1) over the line y = x gives
Over y = x: swap the coordinates.
Rotating (-4, 5) 90° counterclockwise about the origin gives
90° CCW: (x, y) → (−y, x).
Rotating (5, 1) 90° counterclockwise about the origin gives
90° CCW: (x, y) → (−y, x).
Rotating (6, -4) 90° counterclockwise about the origin gives
90° CCW: (x, y) → (−y, x).
Reflecting (1, 7) over the line y = x gives
Over y = x: swap the coordinates.
Rotating (3, 2) 90° counterclockwise about the origin gives
90° CCW: (x, y) → (−y, x).
Reflecting (2, -6) over the line y = x gives
Over y = x: swap the coordinates.
Rotating (-3, -2) 90° counterclockwise about the origin gives
90° CCW: (x, y) → (−y, x).
Rotating (2, -6) 90° counterclockwise about the origin gives
90° CCW: (x, y) → (−y, x).
Reflecting (-4, 5) over the line y = x gives
Over y = x: swap the coordinates.
A cylinder has radius 3 and height 10. Its volume is:
V = πr²h = π(9)(10) = 90π.
A cone has radius 3 and height 10. Its volume is:
V = ⅓πr²h = ⅓π(9)(10) = 30π.
A sphere has radius 3. Its volume is:
V = 4⁄3 πr³ = 4⁄3 π(27) = 36π.
Rotating a rectangle about one of its sides sweeps out a:
Spinning a rectangle around a side produces a cylinder.
A sphere has radius 3. Its surface area is
SA = 4πr² = 4π(9) = 36π.
Rotating a semicircle about its diameter produces a
Spinning a semicircle around its straight edge (diameter) sweeps out a full sphere.
A region has a population of 500,000 over 2,000 square miles. Its population density is
500,000 ÷ 2,000 = 250 people per square mile.
A sphere has a volume of 36π. Its radius is
(4/3)πr³ = 36π → r³ = 27 → r = 3.
A cylinder has radius 2 and height 9. Its volume is
V = πr²h = π(4)(9) = 36π.
A cone has radius 6 and height 5. Its volume is
V = ⅓πr²h = ⅓π(36)(5) = 60π.
A sphere has radius 6. Its volume is
V = 4⁄3 πr³ = 4⁄3 π(216) = 288π.
A plane slices a sphere through any point. The cross-section is a
Every cross-section of a sphere is a circle.
A cylinder has volume 250π and radius 5. Its height is
250π = π(25)h → h = 10.
A cone has radius 9 and slant height 15. Its volume is
Height = √(15² − 9²) = 12. V = ⅓π(81)(12) = 324π.
A sphere has surface area 100π. Its volume is
4πr² = 100π → r = 5. V = 4/3 π(125) = 500π/3.
A circular pool has a 20-ft diameter and is 4 ft deep everywhere. Its volume, to the nearest cubic foot, is
V = π(10²)(4) = 400π ≈ 1257 ft³.
A metal block measures 8 cm × 5 cm × 4 cm and has a mass of 1248 g. Its density is
V = 160 cm³. Density = 1248/160 = 7.8 g/cm³.
A hemisphere has radius 6. Its volume is
Half a sphere: ½ · 4/3 π(216) = 144π.
A 5 × 3 rectangle is rotated about its LONGER side. The volume of the resulting solid is
Cylinder with height 5 (the axis) and radius 3: V = π(9)(5) = 45π.
A plane parallel to the base slices a square pyramid halfway up. The cross-section is a
Slices parallel to the base of a square pyramid are smaller squares.
Find the volume of the cylinder, in terms of π.
V = πr²h = π(16)(9) = 144π.
Find the volume of the cone, in terms of π.
V = ⅓πr²h = ⅓π(36)(8) = 96π.
A conical pile of gravel has radius and height both 4 ft. If a cart carries 6 ft³ per trip, the fewest trips to move the pile is
V = ⅓π(16)(4) ≈ 67.0 ft³ → 67.0/6 ≈ 11.2 → round UP to 12 trips.
A sphere has volume 288π. Its radius is
4/3 πr³ = 288π → r³ = 216 → r = 6.
A cylindrical rain barrel has diameter 4 ft and height 10 ft. Its volume, to the nearest tenth, is
r = 2 → V = π(4)(10) = 40π ≈ 125.7 ft³.
A solid is a 10×4×2 prism topped by a pyramid of height 6 on the same 10×4 base. Total volume ×2.7 g/cm³ density gives a mass of
Prism 80 + pyramid ⅓(40)(6)=80 → 160 cm³ × 2.7 = 432 g.
A plane slices a cylinder perpendicular to its bases, passing through the axis. The cross-section is a
A vertical cut through the axis of a cylinder is a rectangle.
Gold has density 19.3 g/cm³. A bar of volume 25 cm³ has mass
mass = density × volume = 19.3 × 25 = 482.5 g.
A cylinder has radius 3 and height 7. Its volume is
V = πr²h = 63π.
A cone has radius 5 and height 3. Its volume is
V = ⅓πr²h = 25π.
A cone has radius 6 and height 5. Its volume is
V = ⅓πr²h = 60π.
A cylinder has radius 3 and height 11. Its volume is
V = πr²h = 99π.
A cylinder has radius 4 and height 5. Its volume is
V = πr²h = 80π.
A cylinder has radius 5 and height 6. Its volume is
V = πr²h = 150π.
A cone has radius 2 and height 12. Its volume is
V = ⅓πr²h = 16π.
A cone has radius 9 and height 4. Its volume is
V = ⅓πr²h = 108π.
A cone has radius 4 and height 9. Its volume is
V = ⅓πr²h = 48π.
Two complementary angles are in the ratio 2:3. The larger angle measures
2x + 3x = 90 → x = 18 → angles 36° and 54° → larger = 54°.
Two complementary angles are in the ratio 4:5. The larger angle measures
4x + 5x = 90 → x = 10 → angles 40° and 50° → larger = 50°.
Two complementary angles are in the ratio 3:7. The larger angle measures
3x + 7x = 90 → x = 9 → angles 27° and 63° → larger = 63°.
Two complementary angles are in the ratio 1:2. The larger angle measures
1x + 2x = 90 → x = 30 → angles 30° and 60° → larger = 60°.
Two complementary angles are in the ratio 1:4. The larger angle measures
1x + 4x = 90 → x = 18 → angles 18° and 72° → larger = 72°.
Vertical angles measure (4x + 31)° and (6x + 7)°. What is the SUPPLEMENT of either angle?
Vertical angles are congruent: 4x + 31 = 6x + 7 → x = 12 → angle = 79° → supplement = 101°.
Vertical angles measure (7x + 18)° and (6x + 24)°. What is the SUPPLEMENT of either angle?
Vertical angles are congruent: 7x + 18 = 6x + 24 → x = 6 → angle = 60° → supplement = 120°.
Vertical angles measure (3x + 7)° and (2x + 31)°. What is the SUPPLEMENT of either angle?
Vertical angles are congruent: 3x + 7 = 2x + 31 → x = 24 → angle = 79° → supplement = 101°.
Vertical angles measure (6x + 1)° and (3x + 25)°. What is the SUPPLEMENT of either angle?
Vertical angles are congruent: 6x + 1 = 3x + 25 → x = 8 → angle = 49° → supplement = 131°.
Vertical angles measure (7x + 27)° and (5x + 47)°. What is the SUPPLEMENT of either angle?
Vertical angles are congruent: 7x + 27 = 5x + 47 → x = 10 → angle = 97° → supplement = 83°.
Three angles around a point measure (3x)°, (4x)°, and (5x)°. The LARGEST angle is
Angles around a point total 360°: 12x = 360 → x = 30 → largest = 150°.
Three angles around a point measure (8x)°, (3x)°, and (4x)°. The LARGEST angle is
Angles around a point total 360°: 15x = 360 → x = 24 → largest = 192°.
Three angles around a point measure (7x)°, (8x)°, and (3x)°. The LARGEST angle is
Angles around a point total 360°: 18x = 360 → x = 20 → largest = 160°.
Three angles around a point measure (8x)°, (5x)°, and (7x)°. The LARGEST angle is
Angles around a point total 360°: 20x = 360 → x = 18 → largest = 144°.
Three angles around a point measure (7x)°, (5x)°, and (8x)°. The LARGEST angle is
Angles around a point total 360°: 20x = 360 → x = 18 → largest = 144°.
B is between A and C. If AB = 2x + 8, BC = 3x + 18, and AC = 56, then AB =
AB + BC = AC: (2x+8) + (3x+18) = 56 → x = 6 → AB = 20.
B is between A and C. If AB = 2x + 4, BC = 3x + 8, and AC = 57, then AB =
AB + BC = AC: (2x+4) + (3x+8) = 57 → x = 9 → AB = 22.
B is between A and C. If AB = 2x + 3, BC = 2x + 7, and AC = 62, then AB =
AB + BC = AC: (2x+3) + (2x+7) = 62 → x = 13 → AB = 29.
B is between A and C. If AB = 2x + 9, BC = 2x + 21, and AC = 58, then AB =
AB + BC = AC: (2x+9) + (2x+21) = 58 → x = 7 → AB = 23.
B is between A and C. If AB = 2x + 10, BC = 4x + 20, and AC = 54, then AB =
AB + BC = AC: (2x+10) + (4x+20) = 54 → x = 4 → AB = 18.
B is the midpoint of AC. If AB = 2x + 2 and AC = 3x + 10, then AC =
AC = 2·AB: 3x + 10 = 2(2x + 2) → x = 6 → AC = 28.
B is the midpoint of AC. If AB = 4x + 12 and AC = 6x + 50, then AC =
AC = 2·AB: 6x + 50 = 2(4x + 12) → x = 13 → AC = 128.
B is the midpoint of AC. If AB = 3x + 7 and AC = 2x + 50, then AC =
AC = 2·AB: 2x + 50 = 2(3x + 7) → x = 9 → AC = 68.
B is the midpoint of AC. If AB = 2x + 9 and AC = 5x + 15, then AC =
AC = 2·AB: 5x + 15 = 2(2x + 9) → x = 3 → AC = 30.
B is the midpoint of AC. If AB = 2x + 15 and AC = 6x + 10, then AC =
AC = 2·AB: 6x + 10 = 2(2x + 15) → x = 10 → AC = 70.
Ray BD bisects ∠ABC. If m∠ABD = (2x + 1)° and m∠ABC = 58°, then x =
Bisector splits the angle evenly: m∠ABD = ½(58) = 29° → 2x + 1 = 29 → x = 14.
Ray BD bisects ∠ABC. If m∠ABD = (4x + 16)° and m∠ABC = 80°, then x =
Bisector splits the angle evenly: m∠ABD = ½(80) = 40° → 4x + 16 = 40 → x = 6.
Ray BD bisects ∠ABC. If m∠ABD = (2x + 4)° and m∠ABC = 60°, then x =
Bisector splits the angle evenly: m∠ABD = ½(60) = 30° → 2x + 4 = 30 → x = 13.
Ray BD bisects ∠ABC. If m∠ABD = (2x + 29)° and m∠ABC = 66°, then x =
Bisector splits the angle evenly: m∠ABD = ½(66) = 33° → 2x + 29 = 33 → x = 2.
Ray BD bisects ∠ABC. If m∠ABD = (4x + 6)° and m∠ABC = 36°, then x =
Bisector splits the angle evenly: m∠ABD = ½(36) = 18° → 4x + 6 = 18 → x = 3.
An angle measures 15°. The DIFFERENCE between its supplement and its complement is
Supplement = 180−15 = 165°. Complement = 90−15 = 75°. Difference = 165−75 = 90°.
An angle measures 11°. The DIFFERENCE between its supplement and its complement is
Supplement = 180−11 = 169°. Complement = 90−11 = 79°. Difference = 169−79 = 90°.
An angle measures 35°. The DIFFERENCE between its supplement and its complement is
Supplement = 180−35 = 145°. Complement = 90−35 = 55°. Difference = 145−55 = 90°.
An angle measures 52°. The DIFFERENCE between its supplement and its complement is
Supplement = 180−52 = 128°. Complement = 90−52 = 38°. Difference = 128−38 = 90°.
An angle measures 58°. The DIFFERENCE between its supplement and its complement is
Supplement = 180−58 = 122°. Complement = 90−58 = 32°. Difference = 122−32 = 90°.
Ray BD bisects ∠ABC. If m∠ABD = (6x + 1)° and m∠ABC = 110°, then x =
Bisector splits the angle evenly: m∠ABD = ½(110) = 55° → 6x + 1 = 55 → x = 9.
Ray BD bisects ∠ABC. If m∠ABD = (5x + 12)° and m∠ABC = 124°, then x =
Bisector splits the angle evenly: m∠ABD = ½(124) = 62° → 5x + 12 = 62 → x = 10.
B is between A and C. If AB = 2x + 6, BC = 5x + 16, and AC = 43, then AB =
AB + BC = AC: (2x+6) + (5x+16) = 43 → x = 3 → AB = 12.
An angle measures 49°. The DIFFERENCE between its supplement and its complement is
Supplement = 180−49 = 131°. Complement = 90−49 = 41°. Difference = 131−41 = 90°.
Three angles around a point measure (6x)°, (4x)°, and (8x)°. The LARGEST angle is
Angles around a point total 360°: 18x = 360 → x = 20 → largest = 160°.
Alternate interior angles measure (5x + 37)° and (6x + 7)°. Each measures
Alternate interior angles are congruent: 5x + 37 = 6x + 7 → x = 30 → each = 187°.
Alternate exterior angles measure (4x + 32)° and (2x + 58)°. Each measures
Alternate exterior angles are congruent: 4x + 32 = 2x + 58 → x = 13 → each = 84°.
Alternate exterior angles measure (4x + 24)° and (6x + 4)°. Each measures
Alternate exterior angles are congruent: 4x + 24 = 6x + 4 → x = 10 → each = 64°.
Alternate interior angles measure (5x + 12)° and (4x + 16)°. Each measures
Alternate interior angles are congruent: 5x + 12 = 4x + 16 → x = 4 → each = 32°.
Alternate exterior angles measure (2x + 26)° and (3x + 12)°. Each measures
Alternate exterior angles are congruent: 2x + 26 = 3x + 12 → x = 14 → each = 54°.
Same-side interior angles measure (6x + 27)° and (5x + 4)°. The smaller one is
Same-side interior angles are supplementary: (6x+27) + (5x+4) = 180 → x = 16 → angles 123° and 84° → smaller = 84°.
Same-side exterior angles measure (5x + 19)° and (6x + 37)°. The smaller one is
Same-side exterior angles are supplementary: (5x+19) + (6x+37) = 180 → x = 13 → angles 84° and 115° → smaller = 84°.
Same-side exterior angles measure (4x + 23)° and (2x + 42)°. The smaller one is
Same-side exterior angles are supplementary: (4x+23) + (2x+42) = 180 → x = 23 → angles 115° and 88° → smaller = 88°.
Same-side interior angles measure (5x + 27)° and (2x + 40)°. The smaller one is
Same-side interior angles are supplementary: (5x+27) + (2x+40) = 180 → x = 20 → angles 127° and 80° → smaller = 80°.
Same-side exterior angles measure (2x + 5)° and (6x + 20)°. The smaller one is
Same-side exterior angles are supplementary: (2x+5) + (6x+20) = 180 → x = 20 → angles 45° and 140° → smaller = 45°.
A line passes through (3, -4) and (6, -2). An equation of the line through (-5, 5) parallel to it is
Slope between the given points = (2)/(3) = 2/3. Parallel lines share slope, so through (-5,5): y − 5 = 2/3(x − -5).
A line passes through (-1, -6) and (3, -3). An equation of the line through (5, -4) parallel to it is
Slope between the given points = (3)/(4) = 3/4. Parallel lines share slope, so through (5,-4): y − -4 = 3/4(x − 5).
A line passes through (-5, 6) and (0, 8). An equation of the line through (3, -4) parallel to it is
Slope between the given points = (2)/(5) = 2/5. Parallel lines share slope, so through (3,-4): y − -4 = 2/5(x − 3).
A line passes through (6, 4) and (10, 7). An equation of the line through (1, -1) parallel to it is
Slope between the given points = (3)/(4) = 3/4. Parallel lines share slope, so through (1,-1): y − -1 = 3/4(x − 1).
A line passes through (5, 1) and (8, 3). An equation of the line through (-3, 1) parallel to it is
Slope between the given points = (2)/(3) = 2/3. Parallel lines share slope, so through (-3,1): y − 1 = 2/3(x − -3).
Line ℓ has slope 3/4. Line m is perpendicular to ℓ and has slope (2x)/3. Find x.
Perpendicular slopes multiply to −1. Solving (2x)/3 = −4/3 gives x = -2.
Lines p, q, and r are all parallel, cut by transversal t. If one angle at line p is (5x + 11)° and its corresponding angle at line r is 101°, then x =
Corresponding angles across parallel lines are equal: 5x + 11 = 101 → x = 18.
Lines p, q, and r are all parallel, cut by transversal t. If one angle at line p is (3x + 8)° and its corresponding angle at line r is 68°, then x =
Corresponding angles across parallel lines are equal: 3x + 8 = 68 → x = 20.
Lines p, q, and r are all parallel, cut by transversal t. If one angle at line p is (4x + 20)° and its corresponding angle at line r is 40°, then x =
Corresponding angles across parallel lines are equal: 4x + 20 = 40 → x = 5.
Lines p, q, and r are all parallel, cut by transversal t. If one angle at line p is (3x + 7)° and its corresponding angle at line r is 55°, then x =
Corresponding angles across parallel lines are equal: 3x + 7 = 55 → x = 16.
Lines p, q, and r are all parallel, cut by transversal t. If one angle at line p is (4x + 12)° and its corresponding angle at line r is 36°, then x =
Corresponding angles across parallel lines are equal: 4x + 12 = 36 → x = 6.
Two lines are cut by a transversal. Which condition guarantees the lines are parallel?
The Converse of the Alternate Interior Angles Theorem: if alternate interior angles are congruent, the lines must be parallel.
A line has slope 9/4. A line parallel to it also has slope
Parallel lines have equal slopes.
A line has slope 8/7. A line parallel to it also has slope
Parallel lines have equal slopes.
A line has slope 7/3. A line parallel to it also has slope
Parallel lines have equal slopes.
A line has slope 6/7. A line parallel to it also has slope
Parallel lines have equal slopes.
A line has slope 3/5. A line parallel to it also has slope
Parallel lines have equal slopes.
Lines p, q, and r are all parallel, cut by transversal t. If one angle at line p is (4x + 20)° and its corresponding angle at line r is 44°, then x =
Corresponding angles across parallel lines are equal: 4x + 20 = 44 → x = 6.
A line passes through (-3, 4) and (2, 6). An equation of the line through (1, 4) parallel to it is
Slope between the given points = (2)/(5) = 2/5. Parallel lines share slope, so through (1,4): y − 4 = 2/5(x − 1).
Lines p, q, and r are all parallel, cut by transversal t. If one angle at line p is (3x + 6)° and its corresponding angle at line r is 54°, then x =
Corresponding angles across parallel lines are equal: 3x + 6 = 54 → x = 16.
A line has slope 5/8. A line parallel to it also has slope
Parallel lines have equal slopes.
Same-side interior angles measure (6x + 5)° and (5x + 37)°. The smaller one is
Same-side interior angles are supplementary: (6x+5) + (5x+37) = 180 → x = 13 → angles 83° and 102° → smaller = 83°.
Alternate exterior angles measure (6x + 37)° and (4x + 59)°. Each measures
Alternate exterior angles are congruent: 6x + 37 = 4x + 59 → x = 11 → each = 103°.
A line has slope 3/7. A line parallel to it also has slope
Parallel lines have equal slopes.
A line has slope 2/4. A line parallel to it also has slope
Parallel lines have equal slopes.
Alternate interior angles measure (6x + 16)° and (3x + 49)°. Each measures
Alternate interior angles are congruent: 6x + 16 = 3x + 49 → x = 11 → each = 82°.
A line has slope 9/2. A line parallel to it also has slope
Parallel lines have equal slopes.
Alternate interior angles measure (4x + 29)° and (5x + 12)°. Each measures
Alternate interior angles are congruent: 4x + 29 = 5x + 12 → x = 17 → each = 97°.
Same-side interior angles measure (3x + 3)° and (3x + 36)°. The smaller one is
Same-side interior angles are supplementary: (3x+3) + (3x+36) = 180 → x = 24 → angles 75° and 108° → smaller = 75°.
A line passes through (-2, -3) and (0, -4). An equation of the line through (4, 6) parallel to it is
Slope between the given points = (-1)/(2) = -1/2. Parallel lines share slope, so through (4,6): y − 6 = -1/2(x − 4).
The angles of a triangle measure (2x+14)°, (3x+2)°, and (4x+38)°. The LARGEST angle is
Angles sum to 180: 9x + 54 = 180 → x = 14 → angles 42°, 44°, 94° → largest = 94°.
The angles of a triangle measure (2x+17)°, (1x+8)°, and (3x+23)°. The LARGEST angle is
Angles sum to 180: 6x + 48 = 180 → x = 22 → angles 61°, 30°, 89° → largest = 89°.
The angles of a triangle measure (2x+2)°, (4x+20)°, and (1x+18)°. The LARGEST angle is
Angles sum to 180: 7x + 40 = 180 → x = 20 → angles 42°, 100°, 38° → largest = 100°.
The angles of a triangle measure (3x+20)°, (2x+2)°, and (1x+32)°. The LARGEST angle is
Angles sum to 180: 6x + 54 = 180 → x = 21 → angles 83°, 44°, 53° → largest = 83°.
The angles of a triangle measure (4x+15)°, (3x+18)°, and (2x+21)°. The LARGEST angle is
Angles sum to 180: 9x + 54 = 180 → x = 14 → angles 71°, 60°, 49° → largest = 71°.
An exterior angle of a triangle has two remote interior angles measuring 66° and 74°. The exterior angle measures
Exterior Angle Theorem: exterior angle = sum of remote interior angles = 66 + 74 = 140°.
An exterior angle of a triangle has two remote interior angles measuring 76° and 45°. The exterior angle measures
Exterior Angle Theorem: exterior angle = sum of remote interior angles = 76 + 45 = 121°.
An exterior angle of a triangle has two remote interior angles measuring 31° and 30°. The exterior angle measures
Exterior Angle Theorem: exterior angle = sum of remote interior angles = 31 + 30 = 61°.
An exterior angle of a triangle has two remote interior angles measuring 49° and 68°. The exterior angle measures
Exterior Angle Theorem: exterior angle = sum of remote interior angles = 49 + 68 = 117°.
An exterior angle of a triangle has two remote interior angles measuring 22° and 60°. The exterior angle measures
Exterior Angle Theorem: exterior angle = sum of remote interior angles = 22 + 60 = 82°.
An exterior angle measures (5x + 22)°; its remote interior angles are (3x + 30)° and 28°. The exterior angle is
Exterior = sum of remote interiors: 5x+22 = (3x+30) + 28 → x = 18 → exterior = 112°.
An exterior angle measures (5x + 26)°; its remote interior angles are (3x + 37)° and 23°. The exterior angle is
Exterior = sum of remote interiors: 5x+26 = (3x+37) + 23 → x = 17 → exterior = 111°.
An exterior angle measures (3x + 29)°; its remote interior angles are (1x + 60)° and 15°. The exterior angle is
Exterior = sum of remote interiors: 3x+29 = (1x+60) + 15 → x = 23 → exterior = 98°.
An exterior angle measures (4x + 2)°; its remote interior angles are (2x + 46)° and 26°. The exterior angle is
Exterior = sum of remote interiors: 4x+2 = (2x+46) + 26 → x = 35 → exterior = 142°.
An exterior angle measures (4x + 27)°; its remote interior angles are (3x + 40)° and 20°. The exterior angle is
Exterior = sum of remote interiors: 4x+27 = (3x+40) + 20 → x = 33 → exterior = 159°.
In isosceles triangle ABC, AB ≅ AC, and the base angles each measure 56°. The exterior angle at a BASE vertex measures
The exterior angle at a base vertex is supplementary to the base angle: 180 − 56 = 124°.
In isosceles triangle ABC, AB ≅ AC, and the base angles each measure 44°. The exterior angle at a BASE vertex measures
The exterior angle at a base vertex is supplementary to the base angle: 180 − 44 = 136°.
In isosceles triangle ABC, AB ≅ AC, and the base angles each measure 58°. The exterior angle at a BASE vertex measures
The exterior angle at a base vertex is supplementary to the base angle: 180 − 58 = 122°.
In isosceles triangle ABC, AB ≅ AC, and the base angles each measure 79°. The exterior angle at a BASE vertex measures
The exterior angle at a base vertex is supplementary to the base angle: 180 − 79 = 101°.
In isosceles triangle ABC, AB ≅ AC, and the base angles each measure 63°. The exterior angle at a BASE vertex measures
The exterior angle at a base vertex is supplementary to the base angle: 180 − 63 = 117°.
Two sides of a triangle measure 15 and 15. The length of the third side could be any value between
Triangle Inequality: the third side is between |15−15| = 0 and 15+15 = 30 (exclusive).
Two sides of a triangle measure 20 and 10. The length of the third side could be any value between
Triangle Inequality: the third side is between |20−10| = 10 and 20+10 = 30 (exclusive).
Two sides of a triangle measure 19 and 6. The length of the third side could be any value between
Triangle Inequality: the third side is between |19−6| = 13 and 19+6 = 25 (exclusive).
Two sides of a triangle measure 19 and 8. The length of the third side could be any value between
Triangle Inequality: the third side is between |19−8| = 11 and 19+8 = 27 (exclusive).
Isosceles triangle ABC has AB ≅ AC. The base angles each measure (3x + 29)°, and the vertex angle measures 86°. Find x.
Base angles are equal and sum with vertex to 180: 2(3x+29) + 86 = 180 → x = 6.
Isosceles triangle ABC has AB ≅ AC. The base angles each measure (2x + 20)°, and the vertex angle measures 124°. Find x.
Base angles are equal and sum with vertex to 180: 2(2x+20) + 124 = 180 → x = 4.
Isosceles triangle ABC has AB ≅ AC. The base angles each measure (3x + 9)°, and the vertex angle measures 120°. Find x.
Base angles are equal and sum with vertex to 180: 2(3x+9) + 120 = 180 → x = 7.
Isosceles triangle ABC has AB ≅ AC. The base angles each measure (3x + 14)°, and the vertex angle measures 86°. Find x.
Base angles are equal and sum with vertex to 180: 2(3x+14) + 86 = 180 → x = 11.
A median of a triangle measures 30 units. The distance from the vertex to the centroid is
The centroid divides each median 2:1 from the vertex: 30 × ⅔ = 20.
A median of a triangle measures 27 units. The distance from the vertex to the centroid is
The centroid divides each median 2:1 from the vertex: 27 × ⅔ = 18.
A median of a triangle measures 33 units. The distance from the vertex to the centroid is
The centroid divides each median 2:1 from the vertex: 33 × ⅔ = 22.
A median of a triangle measures 15 units. The distance from the vertex to the centroid is
The centroid divides each median 2:1 from the vertex: 15 × ⅔ = 10.
A triangle has sides 10, 13, and 16. It is
Compare 16² = 256 to 10²+13² = 269: less → acute triangle.
A triangle has sides 9, 40, and 41. It is
Compare 41² = 1681 to 9²+40² = 1681: equal → right triangle.
A triangle has sides 7, 24, and 25. It is
Compare 25² = 625 to 7²+24² = 625: equal → right triangle.
A triangle has sides 10, 10, and 14. It is
Compare 14² = 196 to 10²+10² = 200: less → acute triangle.
A triangle has sides 5, 12, and 13. It is
Compare 13² = 169 to 5²+12² = 169: equal → right triangle.
Two sides of a triangle measure 15 and 14. The length of the third side could be any value between
Triangle Inequality: the third side is between |15−14| = 1 and 15+14 = 29 (exclusive).
Isosceles triangle ABC has AB ≅ AC. The base angles each measure (1x + 16)°, and the vertex angle measures 138°. Find x.
Base angles are equal and sum with vertex to 180: 2(1x+16) + 138 = 180 → x = 5.
An exterior angle of a triangle has two remote interior angles measuring 72° and 48°. The exterior angle measures
Exterior Angle Theorem: exterior angle = sum of remote interior angles = 72 + 48 = 120°.
In △ABC and △DEF, AB ≅ DE, ∠B ≅ ∠E, BC ≅ EF, where ∠B is between AB and BC. The triangles are congruent by
The given parts match the SAS congruence pattern.
In △ABC and △DEF, AB ≅ DE, BC ≅ EF, AC ≅ DF. The triangles are congruent by
The given parts match the SSS congruence pattern.
In △ABC and △DEF, ∠B and ∠E are right angles, AB ≅ DE (hypotenuses), AC ≅ DF (a leg). The triangles are congruent by
The given parts match the HL congruence pattern.
In △ABC and △DEF, ∠A ≅ ∠D, ∠B ≅ ∠E, BC ≅ EF, where BC is NOT between the two angle pairs. The triangles are congruent by
The given parts match the AAS congruence pattern.
In △ABC and △DEF, ∠A ≅ ∠D, AB ≅ DE, ∠B ≅ ∠E, where AB is between ∠A and ∠B. The triangles are congruent by
The given parts match the ASA congruence pattern.
△ABC ≅ △DEF with AB = 4x + 20 and DE = 3x + 35. AB =
Corresponding sides are equal (CPCTC): 4x+20 = 3x+35 → x = 15 → AB = 80.
△ABC ≅ △DEF with AB = 4x + 9 and DE = 3x + 32. AB =
Corresponding sides are equal (CPCTC): 4x+9 = 3x+32 → x = 23 → AB = 101.
△ABC ≅ △DEF with AB = 5x + 23 and DE = 2x + 38. AB =
Corresponding sides are equal (CPCTC): 5x+23 = 2x+38 → x = 5 → AB = 48.
△ABC ≅ △DEF with AB = 5x + 2 and DE = 3x + 24. AB =
Corresponding sides are equal (CPCTC): 5x+2 = 3x+24 → x = 11 → AB = 57.
△ABC ≅ △DEF with AB = 3x + 25 and DE = 5x + 17. AB =
Corresponding sides are equal (CPCTC): 3x+25 = 5x+17 → x = 4 → AB = 37.
△PQR ≅ △XYZ and m∠Q = 43°. Then m∠Y =
Corresponding angles of congruent triangles are equal (CPCTC).
△PQR ≅ △XYZ and m∠Q = 56°. Then m∠Y =
Corresponding angles of congruent triangles are equal (CPCTC).
△PQR ≅ △XYZ and m∠Q = 57°. Then m∠Y =
Corresponding angles of congruent triangles are equal (CPCTC).
△PQR ≅ △XYZ and m∠Q = 61°. Then m∠Y =
Corresponding angles of congruent triangles are equal (CPCTC).
△PQR ≅ △XYZ and m∠Q = 79°. Then m∠Y =
Corresponding angles of congruent triangles are equal (CPCTC).
Two triangles share side BD, with ∠A ≅ ∠C and AB ≅ CD marked. To prove congruence by SAS, the missing justification for BD ≅ BD is
A side shared by both triangles is congruent to itself — the Reflexive Property.
Two triangles overlap at point M, sharing vertical angles ∠AMB and ∠CMD, with AM ≅ CM marked. For SAS you also need
SAS needs the second side forming the vertical angle: BM ≅ DM, since ∠AMB ≅ ∠CMD by the Vertical Angles Theorem.
△ABC is mapped onto △A'B'C' by a rotation of 90° about the origin. Which statement must be true?
A rotation of 90° about the origin is a rigid motion — it preserves distance and angle measure, so the image is congruent to the original.
△ABC is mapped onto △A'B'C' by a reflection over the y-axis. Which statement must be true?
A reflection over the y-axis is a rigid motion — it preserves distance and angle measure, so the image is congruent to the original.
△ABC is mapped onto △A'B'C' by a translation. Which statement must be true?
A translation is a rigid motion — it preserves distance and angle measure, so the image is congruent to the original.
In △ABC, ∠B ≅ ∠C. Which conclusion is justified by the Converse of the Isosceles Triangle Theorem?
If two angles of a triangle are congruent, the sides opposite them are congruent: AB ≅ AC.
△ABD ≅ △CBD share side BD. If AD = 3x + 10 and CD = 4x + 6, then AD =
CPCTC: AD = CD → 3x+10 = 4x+6 → x = 4 → AD = 22.
△ABD ≅ △CBD share side BD. If AD = 3x + 13 and CD = 2x + 31, then AD =
CPCTC: AD = CD → 3x+13 = 2x+31 → x = 18 → AD = 67.
△ABD ≅ △CBD share side BD. If AD = 3x + 12 and CD = 2x + 25, then AD =
CPCTC: AD = CD → 3x+12 = 2x+25 → x = 13 → AD = 51.
△ABD ≅ △CBD share side BD. If AD = 2x + 20 and CD = 3x + 4, then AD =
CPCTC: AD = CD → 2x+20 = 3x+4 → x = 16 → AD = 52.
△ABD ≅ △CBD share side BD. If AD = 2x + 16 and CD = 3x + 7, then AD =
CPCTC: AD = CD → 2x+16 = 3x+7 → x = 9 → AD = 34.
△ABD ≅ △CBD share side BD. If AD = 2x + 19 and CD = 3x + 16, then AD =
CPCTC: AD = CD → 2x+19 = 3x+16 → x = 3 → AD = 25.
△ABD ≅ △CBD share side BD. If AD = 4x + 20 and CD = 3x + 25, then AD =
CPCTC: AD = CD → 4x+20 = 3x+25 → x = 5 → AD = 40.
△ABD ≅ △CBD share side BD. If AD = 3x + 5 and CD = 2x + 11, then AD =
CPCTC: AD = CD → 3x+5 = 2x+11 → x = 6 → AD = 23.
△PQR ≅ △XYZ and m∠Q = 49°. Then m∠Y =
Corresponding angles of congruent triangles are equal (CPCTC).
△PQR ≅ △XYZ and m∠Q = 75°. Then m∠Y =
Corresponding angles of congruent triangles are equal (CPCTC).
△PQR ≅ △XYZ and m∠Q = 72°. Then m∠Y =
Corresponding angles of congruent triangles are equal (CPCTC).
△PQR ≅ △XYZ and m∠Q = 22°. Then m∠Y =
Corresponding angles of congruent triangles are equal (CPCTC).
△ABC ≅ △DEF with AB = 6x + 4 and DE = 4x + 22. AB =
Corresponding sides are equal (CPCTC): 6x+4 = 4x+22 → x = 9 → AB = 58.
△ABD ≅ △CBD share side BD. If AD = 4x + 9 and CD = 3x + 28, then AD =
CPCTC: AD = CD → 4x+9 = 3x+28 → x = 19 → AD = 85.
△ABD ≅ △CBD share side BD. If AD = 4x + 12 and CD = 3x + 31, then AD =
CPCTC: AD = CD → 4x+12 = 3x+31 → x = 19 → AD = 88.
△ABC ≅ △DEF with AB = 4x + 2 and DE = 2x + 14. AB =
Corresponding sides are equal (CPCTC): 4x+2 = 2x+14 → x = 6 → AB = 26.
△ABC ≅ △DEF with AB = 5x + 23 and DE = 6x + 19. AB =
Corresponding sides are equal (CPCTC): 5x+23 = 6x+19 → x = 4 → AB = 43.
△ABD ≅ △CBD share side BD. If AD = 3x + 7 and CD = 2x + 15, then AD =
CPCTC: AD = CD → 3x+7 = 2x+15 → x = 8 → AD = 31.
△ABC ≅ △DEF with AB = 4x + 25 and DE = 5x + 6. AB =
Corresponding sides are equal (CPCTC): 4x+25 = 5x+6 → x = 19 → AB = 101.
Two similar triangles have corresponding sides in the ratio 4:9. If the smaller triangle's perimeter is 16, the larger triangle's perimeter is
Perimeters scale with the side ratio: 16 × 9/4 = 36.
Two similar triangles have corresponding sides in the ratio 4:3. If the smaller triangle's perimeter is 36, the larger triangle's perimeter is
Perimeters scale with the side ratio: 36 × 3/4 = 27.
Two similar triangles have corresponding sides in the ratio 9:6. If the smaller triangle's perimeter is 63, the larger triangle's perimeter is
Perimeters scale with the side ratio: 63 × 6/9 = 42.
Two similar triangles have corresponding sides in the ratio 9:2. If the smaller triangle's perimeter is 81, the larger triangle's perimeter is
Perimeters scale with the side ratio: 81 × 2/9 = 18.
Two similar triangles have corresponding sides in the ratio 5:7. If the smaller triangle's perimeter is 20, the larger triangle's perimeter is
Perimeters scale with the side ratio: 20 × 7/5 = 28.
Two similar polygons have corresponding sides in the ratio 6:4. Their areas are in the ratio
Area ratio = (side ratio)² = 6²:4² = 36 : 16.
Two similar polygons have corresponding sides in the ratio 2:5. Their areas are in the ratio
Area ratio = (side ratio)² = 2²:5² = 4 : 25.
Two similar polygons have corresponding sides in the ratio 5:3. Their areas are in the ratio
Area ratio = (side ratio)² = 5²:3² = 25 : 9.
Two similar polygons have corresponding sides in the ratio 5:2. Their areas are in the ratio
Area ratio = (side ratio)² = 5²:2² = 25 : 4.
Two similar polygons have corresponding sides in the ratio 6:2. Their areas are in the ratio
Area ratio = (side ratio)² = 6²:2² = 36 : 4.
The altitude to the hypotenuse of a right triangle splits it into segments of 12 and 3. The altitude measures
Altitude = √(segment₁ × segment₂) = √(12×3) = √36 = 6.
The altitude to the hypotenuse of a right triangle splits it into segments of 2 and 18. The altitude measures
Altitude = √(segment₁ × segment₂) = √(2×18) = √36 = 6.
The altitude to the hypotenuse of a right triangle splits it into segments of 18 and 2. The altitude measures
Altitude = √(segment₁ × segment₂) = √(18×2) = √36 = 6.
The altitude to the hypotenuse of a right triangle splits it into segments of 4 and 16. The altitude measures
Altitude = √(segment₁ × segment₂) = √(4×16) = √64 = 8.
The altitude to the hypotenuse of a right triangle splits it into segments of 16 and 4. The altitude measures
Altitude = √(segment₁ × segment₂) = √(16×4) = √64 = 8.
In a right triangle, the whole hypotenuse measures 12 and one hypotenuse segment (adjacent to a leg) measures 3. That leg measures
leg² = (adjacent segment)(whole hypotenuse) = 3 × 12 = 36 → leg = 6.
In a right triangle, the whole hypotenuse measures 25 and one hypotenuse segment (adjacent to a leg) measures 16. That leg measures
leg² = (adjacent segment)(whole hypotenuse) = 16 × 25 = 400 → leg = 20.
In a right triangle, the whole hypotenuse measures 25 and one hypotenuse segment (adjacent to a leg) measures 9. That leg measures
leg² = (adjacent segment)(whole hypotenuse) = 9 × 25 = 225 → leg = 15.
In a right triangle, the whole hypotenuse measures 18 and one hypotenuse segment (adjacent to a leg) measures 2. That leg measures
leg² = (adjacent segment)(whole hypotenuse) = 2 × 18 = 36 → leg = 6.
In a right triangle, the whole hypotenuse measures 36 and one hypotenuse segment (adjacent to a leg) measures 9. That leg measures
leg² = (adjacent segment)(whole hypotenuse) = 9 × 36 = 324 → leg = 18.
DE ∥ AC in △ABC, with BD = 15, DA = 6, BE = 10. Then EC =
Side-Splitter: BD/DA = BE/EC → 15/6 = 10/EC → EC = 4.
DE ∥ AC in △ABC, with BD = 10, DA = 15, BE = 8. Then EC =
Side-Splitter: BD/DA = BE/EC → 10/15 = 8/EC → EC = 12.
DE ∥ AC in △ABC, with BD = 12, DA = 8, BE = 9. Then EC =
Side-Splitter: BD/DA = BE/EC → 12/8 = 9/EC → EC = 6.
DE ∥ AC in △ABC, with BD = 5, DA = 8, BE = 15. Then EC =
Side-Splitter: BD/DA = BE/EC → 5/8 = 15/EC → EC = 24.
Two similar solids have volumes in the ratio 1:8. Their surface areas are in the ratio
Side ratio = ∛(1:8) = 1:2 → area ratio = 1²:2² = 1:4.
Two similar solids have volumes in the ratio 8:1. Their surface areas are in the ratio
Side ratio = ∛(8:1) = 2:1 → area ratio = 2²:1² = 4:1.
Two similar solids have volumes in the ratio 8:64. Their surface areas are in the ratio
Side ratio = ∛(8:64) = 2:4 → area ratio = 2²:4² = 4:16.
Two similar solids have volumes in the ratio 125:1. Their surface areas are in the ratio
Side ratio = ∛(125:1) = 5:1 → area ratio = 5²:1² = 25:1.
Two similar solids have surface areas in the ratio 16:9. Their volumes are in the ratio
Side ratio = √(16:9) = 4:3 → volume ratio = 4³:3³ = 64:27.
Two similar solids have surface areas in the ratio 4:25. Their volumes are in the ratio
Side ratio = √(4:25) = 2:5 → volume ratio = 2³:5³ = 8:125.
Two similar solids have surface areas in the ratio 25:4. Their volumes are in the ratio
Side ratio = √(25:4) = 5:2 → volume ratio = 5³:2³ = 125:8.
Two similar solids have surface areas in the ratio 16:4. Their volumes are in the ratio
Side ratio = √(16:4) = 4:2 → volume ratio = 4³:2³ = 64:8.
Solve the proportion: 4/8 = 2/x
Cross-multiply: 4·x = 8·2 → x = 16/4 = 4.
Solve the proportion: 4/4 = 7/x
Cross-multiply: 4·x = 4·7 → x = 28/4 = 7.
Solve the proportion: 2/7 = 22/x
Cross-multiply: 2·x = 7·22 → x = 154/2 = 77.
Solve the proportion: 2/8 = 29/x
Cross-multiply: 2·x = 8·29 → x = 232/2 = 116.
A figure is dilated by scale factor 1.5. Its area is multiplied by
Area scales by k² = 1.5² = 2.2.
A figure is dilated by scale factor 5. Its area is multiplied by
Area scales by k² = 5² = 25.
A figure is dilated by scale factor 3. Its area is multiplied by
Area scales by k² = 3² = 9.
A figure is dilated by scale factor 4. Its area is multiplied by
Area scales by k² = 4² = 16.
A right triangle has legs 12 and 16. The hypotenuse is
√(12²+16²) = √400 = 20.
A right triangle has legs 20 and 48. The hypotenuse is
√(20²+48²) = √2704 = 52.
A right triangle has legs 6 and 8. The hypotenuse is
√(6²+8²) = √100 = 10.
A right triangle has legs 10 and 24. The hypotenuse is
√(10²+24²) = √676 = 26.
A right triangle has hypotenuse 5 and one leg 3. The other leg is
√(5²−3²) = √16 = 4.
A right triangle has hypotenuse 25 and one leg 7. The other leg is
√(25²−7²) = √576 = 24.
A right triangle has hypotenuse 10 and one leg 6. The other leg is
√(10²−6²) = √64 = 8.
A right triangle has hypotenuse 20 and one leg 12. The other leg is
√(20²−12²) = √256 = 16.
In a 45-45-90 triangle, each leg measures 6. The hypotenuse measures
45-45-90: hypotenuse = leg × √2 = 6√2.
In a 45-45-90 triangle, each leg measures 9. The hypotenuse measures
45-45-90: hypotenuse = leg × √2 = 9√2.
In a 45-45-90 triangle, each leg measures 3. The hypotenuse measures
45-45-90: hypotenuse = leg × √2 = 3√2.
In a 45-45-90 triangle, each leg measures 10. The hypotenuse measures
45-45-90: hypotenuse = leg × √2 = 10√2.
In a 30-60-90 triangle, the short leg measures 5. The hypotenuse measures
30-60-90: hypotenuse = 2 × short leg = 10.
In a 30-60-90 triangle, the short leg measures 4. The hypotenuse measures
30-60-90: hypotenuse = 2 × short leg = 8.
In a 30-60-90 triangle, the short leg measures 7. The hypotenuse measures
30-60-90: hypotenuse = 2 × short leg = 14.
In a 30-60-90 triangle, the short leg measures 2. The hypotenuse measures
30-60-90: hypotenuse = 2 × short leg = 4.
In a 30-60-90 triangle, the hypotenuse measures 18. The LONGER leg measures
Short leg = hyp/2 = 9; longer leg = short × √3 = 9√3.
In a 30-60-90 triangle, the hypotenuse measures 14. The LONGER leg measures
Short leg = hyp/2 = 7; longer leg = short × √3 = 7√3.
In a 30-60-90 triangle, the hypotenuse measures 10. The LONGER leg measures
Short leg = hyp/2 = 5; longer leg = short × √3 = 5√3.
In a 30-60-90 triangle, the hypotenuse measures 6. The LONGER leg measures
Short leg = hyp/2 = 3; longer leg = short × √3 = 3√3.
In right triangle ABC, ∠C = 90°, the side opposite ∠A is 10 and adjacent to ∠A is 8. tan(A) =
tan(A) uses opposite=10, adjacent=8, hypotenuse=√164.
In right triangle ABC, ∠C = 90°, the side opposite ∠A is 13 and adjacent to ∠A is 17. cos(A) =
cos(A) uses opposite=13, adjacent=17, hypotenuse=√458.
In right triangle ABC, ∠C = 90°, the side opposite ∠A is 11 and adjacent to ∠A is 6. sin(A) =
sin(A) uses opposite=11, adjacent=6, hypotenuse=√157.
In right triangle ABC, ∠C = 90°, the side opposite ∠A is 9 and adjacent to ∠A is 15. cos(A) =
cos(A) uses opposite=9, adjacent=15, hypotenuse=√306.
From a point 50 ft from the base of a tower, the angle of elevation to the top is 35°. The tower's height, to the nearest foot, is
h = 50·tan(35°) ≈ 35 ft.
From a point 200 ft from the base of a tower, the angle of elevation to the top is 15°. The tower's height, to the nearest foot, is
h = 200·tan(15°) ≈ 54 ft.
From a point 80 ft from the base of a tower, the angle of elevation to the top is 35°. The tower's height, to the nearest foot, is
h = 80·tan(35°) ≈ 56 ft.
From a point 200 ft from the base of a tower, the angle of elevation to the top is 20°. The tower's height, to the nearest foot, is
h = 200·tan(20°) ≈ 73 ft.
From the top of a 100-ft cliff, the angle of depression to a boat is 15°. The horizontal distance to the boat, to the nearest foot, is
d = 100/tan(15°) ≈ 373 ft.
From the top of a 180-ft cliff, the angle of depression to a boat is 35°. The horizontal distance to the boat, to the nearest foot, is
d = 180/tan(35°) ≈ 257 ft.
From the top of a 150-ft cliff, the angle of depression to a boat is 25°. The horizontal distance to the boat, to the nearest foot, is
d = 150/tan(25°) ≈ 322 ft.
From the top of a 200-ft cliff, the angle of depression to a boat is 15°. The horizontal distance to the boat, to the nearest foot, is
d = 200/tan(15°) ≈ 746 ft.
If sin(3x + 17)° = cos(4x + 3)°, then x =
Cofunctions: (3x+17) + (4x+3) = 90 → x = 10.
If sin(2x + 11)° = cos(2x + 19)°, then x =
Cofunctions: (2x+11) + (2x+19) = 90 → x = 15.
If sin(4x + 16)° = cos(3x + 39)°, then x =
Cofunctions: (4x+16) + (3x+39) = 90 → x = 5.
If sin(3x + 2)° = cos(3x + 22)°, then x =
Cofunctions: (3x+2) + (3x+22) = 90 → x = 11.
A ramp rises 2 ft over a horizontal run of 13 ft. The angle it makes with the ground, to the nearest tenth of a degree, is
θ = tan⁻¹(2/13) ≈ 8.7°.
A ramp rises 9 ft over a horizontal run of 12 ft. The angle it makes with the ground, to the nearest tenth of a degree, is
θ = tan⁻¹(9/12) ≈ 36.9°.
A ramp rises 10 ft over a horizontal run of 19 ft. The angle it makes with the ground, to the nearest tenth of a degree, is
θ = tan⁻¹(10/19) ≈ 27.8°.
A ramp rises 4 ft over a horizontal run of 27 ft. The angle it makes with the ground, to the nearest tenth of a degree, is
θ = tan⁻¹(4/27) ≈ 8.4°.
Each interior angle of a regular 8-gon measures
(n−2)·180/n = (8−2)·180/8 = 135°.
Each interior angle of a regular 9-gon measures
(n−2)·180/n = (9−2)·180/9 = 140°.
Each interior angle of a regular 20-gon measures
(n−2)·180/n = (20−2)·180/20 = 162°.
Each interior angle of a regular 12-gon measures
(n−2)·180/n = (12−2)·180/12 = 150°.
Each interior angle of a regular 10-gon measures
(n−2)·180/n = (10−2)·180/10 = 144°.
Each exterior angle of a regular polygon measures 24°. The polygon has
n = 360/24 = 15.
Each exterior angle of a regular polygon measures 18°. The polygon has
n = 360/18 = 20.
Each exterior angle of a regular polygon measures 60°. The polygon has
n = 360/60 = 6.
Each exterior angle of a regular polygon measures 20°. The polygon has
n = 360/20 = 18.
Each exterior angle of a regular polygon measures 15°. The polygon has
n = 360/15 = 24.
Parallelogram diagonals meet at E. If AE = 4x + 6 and EC = 3x + 20, diagonal AC =
Diagonals bisect each other: 4x+6 = 3x+20 → x = 14 → AE = 62 → AC = 124.
Parallelogram diagonals meet at E. If AE = 6x + 5 and EC = 4x + 25, diagonal AC =
Diagonals bisect each other: 6x+5 = 4x+25 → x = 10 → AE = 65 → AC = 130.
Parallelogram diagonals meet at E. If AE = 6x + 17 and EC = 4x + 27, diagonal AC =
Diagonals bisect each other: 6x+17 = 4x+27 → x = 5 → AE = 47 → AC = 94.
Parallelogram diagonals meet at E. If AE = 5x + 1 and EC = 4x + 14, diagonal AC =
Diagonals bisect each other: 5x+1 = 4x+14 → x = 13 → AE = 66 → AC = 132.
Parallelogram diagonals meet at E. If AE = 3x + 19 and EC = 2x + 38, diagonal AC =
Diagonals bisect each other: 3x+19 = 2x+38 → x = 19 → AE = 76 → AC = 152.
A rhombus has perimeter 104 and one diagonal of length 20. The other diagonal measures
Side = 104/4 = 26. Half-diagonals 10.0 and √(26²−10.0²) = 24 → other diagonal = 48.
A rhombus has perimeter 52 and one diagonal of length 24. The other diagonal measures
Side = 52/4 = 13. Half-diagonals 12.0 and √(13²−12.0²) = 5 → other diagonal = 10.
A rhombus has perimeter 52 and one diagonal of length 10. The other diagonal measures
Side = 52/4 = 13. Half-diagonals 5.0 and √(13²−5.0²) = 12 → other diagonal = 24.
A rhombus has perimeter 20 and one diagonal of length 6. The other diagonal measures
Side = 20/4 = 5. Half-diagonals 3.0 and √(5²−3.0²) = 4 → other diagonal = 8.
A rhombus has perimeter 60 and one diagonal of length 18. The other diagonal measures
Side = 60/4 = 15. Half-diagonals 9.0 and √(15²−9.0²) = 12 → other diagonal = 24.
A kite has one pair of opposite angles measuring 127° and 75°. The other two (equal) angles each measure
Quadrilateral angles sum to 360: 127+75+2x = 360 → x = 158°.
A kite has one pair of opposite angles measuring 97° and 147°. The other two (equal) angles each measure
Quadrilateral angles sum to 360: 97+147+2x = 360 → x = 116°.
A kite has one pair of opposite angles measuring 147° and 122°. The other two (equal) angles each measure
Quadrilateral angles sum to 360: 147+122+2x = 360 → x = 91°.
A kite has one pair of opposite angles measuring 135° and 109°. The other two (equal) angles each measure
Quadrilateral angles sum to 360: 135+109+2x = 360 → x = 116°.
A kite has one pair of opposite angles measuring 65° and 136°. The other two (equal) angles each measure
Quadrilateral angles sum to 360: 65+136+2x = 360 → x = 159°.
A trapezoid has parallel bases 11 and 7. Its midsegment measures
Midsegment = ½(base₁+base₂) = ½(11+7) = 9.
A trapezoid has parallel bases 8 and 12. Its midsegment measures
Midsegment = ½(base₁+base₂) = ½(8+12) = 10.
A trapezoid has parallel bases 17 and 13. Its midsegment measures
Midsegment = ½(base₁+base₂) = ½(17+13) = 15.
A trapezoid has parallel bases 9 and 5. Its midsegment measures
Midsegment = ½(base₁+base₂) = ½(9+5) = 7.
A trapezoid has parallel bases 11 and 15. Its midsegment measures
Midsegment = ½(base₁+base₂) = ½(11+15) = 13.
A rectangle has length 6 and width 8. Each diagonal measures
Diagonal = √(6²+8²) = √100 = 10.
A rectangle has length 12 and width 16. Each diagonal measures
Diagonal = √(12²+16²) = √400 = 20.
A rectangle has length 9 and width 12. Each diagonal measures
Diagonal = √(9²+12²) = √225 = 15.
A rectangle has length 18 and width 24. Each diagonal measures
Diagonal = √(18²+24²) = √900 = 30.
A rectangle has length 3 and width 4. Each diagonal measures
Diagonal = √(3²+4²) = √25 = 5.
A convex polygon has 6 sides. The total number of diagonals is
Diagonals = n(n−3)/2 = 6(6−3)/2 = 9.
A convex polygon has 10 sides. The total number of diagonals is
Diagonals = n(n−3)/2 = 10(10−3)/2 = 35.
A convex polygon has 8 sides. The total number of diagonals is
Diagonals = n(n−3)/2 = 8(8−3)/2 = 20.
A convex polygon has 12 sides. The total number of diagonals is
Diagonals = n(n−3)/2 = 12(12−3)/2 = 54.
A convex polygon has 7 sides. The total number of diagonals is
Diagonals = n(n−3)/2 = 7(7−3)/2 = 14.
An inscribed angle intercepts an arc of 200°. The angle measures
Inscribed angle = ½ its intercepted arc = ½(200) = 100°.
An inscribed angle intercepts an arc of 152°. The angle measures
Inscribed angle = ½ its intercepted arc = ½(152) = 76°.
An inscribed angle intercepts an arc of 320°. The angle measures
Inscribed angle = ½ its intercepted arc = ½(320) = 160°.
An inscribed angle intercepts an arc of 60°. The angle measures
Inscribed angle = ½ its intercepted arc = ½(60) = 30°.
An inscribed angle intercepts an arc of 324°. The angle measures
Inscribed angle = ½ its intercepted arc = ½(324) = 162°.
Two chords intersect inside a circle, forming an angle that intercepts arcs of 154° and 69°. The angle measures
Chord-chord angle = ½(sum of intercepted arcs) = ½(154+69) = 111.5°.
Two chords intersect inside a circle, forming an angle that intercepts arcs of 111° and 63°. The angle measures
Chord-chord angle = ½(sum of intercepted arcs) = ½(111+63) = 87°.
Two chords intersect inside a circle, forming an angle that intercepts arcs of 49° and 160°. The angle measures
Chord-chord angle = ½(sum of intercepted arcs) = ½(49+160) = 104.5°.
Two chords intersect inside a circle, forming an angle that intercepts arcs of 66° and 87°. The angle measures
Chord-chord angle = ½(sum of intercepted arcs) = ½(66+87) = 76.5°.
Two chords intersect inside a circle, forming an angle that intercepts arcs of 94° and 144°. The angle measures
Chord-chord angle = ½(sum of intercepted arcs) = ½(94+144) = 119°.
Two secants meet outside a circle, intercepting arcs of 114° and 62°. The angle formed measures
Exterior angle = ½(far arc − near arc) = ½(114−62) = 26°.
Two secants meet outside a circle, intercepting arcs of 156° and 24°. The angle formed measures
Exterior angle = ½(far arc − near arc) = ½(156−24) = 66°.
Two secants meet outside a circle, intercepting arcs of 152° and 27°. The angle formed measures
Exterior angle = ½(far arc − near arc) = ½(152−27) = 62.5°.
Two secants meet outside a circle, intercepting arcs of 298° and 16°. The angle formed measures
Exterior angle = ½(far arc − near arc) = ½(298−16) = 141°.
Two secants meet outside a circle, intercepting arcs of 102° and 30°. The angle formed measures
Exterior angle = ½(far arc − near arc) = ½(102−30) = 36°.
A tangent and a chord meet at the point of tangency, forming an angle that intercepts an arc of 216°. The angle measures
Tangent-chord angle = ½ intercepted arc = ½(216) = 108°.
A tangent and a chord meet at the point of tangency, forming an angle that intercepts an arc of 20°. The angle measures
Tangent-chord angle = ½ intercepted arc = ½(20) = 10°.
A tangent and a chord meet at the point of tangency, forming an angle that intercepts an arc of 144°. The angle measures
Tangent-chord angle = ½ intercepted arc = ½(144) = 72°.
A tangent and a chord meet at the point of tangency, forming an angle that intercepts an arc of 308°. The angle measures
Tangent-chord angle = ½ intercepted arc = ½(308) = 154°.
A tangent and a chord meet at the point of tangency, forming an angle that intercepts an arc of 148°. The angle measures
Tangent-chord angle = ½ intercepted arc = ½(148) = 74°.
Two chords intersect inside a circle. One chord is split into segments 8 and 7; the other into 14 and x. Find x.
Chord segments: 8·7 = 14·x → x = 56/14 = 4.
Two chords intersect inside a circle. One chord is split into segments 6 and 12; the other into 8 and x. Find x.
Chord segments: 6·12 = 8·x → x = 72/8 = 9.
Two chords intersect inside a circle. One chord is split into segments 10 and 14; the other into 7 and x. Find x.
Chord segments: 10·14 = 7·x → x = 140/7 = 20.
Two chords intersect inside a circle. One chord is split into segments 15 and 5; the other into 3 and x. Find x.
Chord segments: 15·5 = 3·x → x = 75/3 = 25.
The circle (x − 3)² + (y − 5)² = 25 has radius
r = √25 = 5.
The circle (x − 6)² + (y − -1)² = 64 has radius
r = √64 = 8.
The circle (x − 3)² + (y − -1)² = 64 has radius
r = √64 = 8.
The circle (x − 0)² + (y − 1)² = 49 has radius
r = √49 = 7.
A circle has radius 12 and a central angle of 120°. The length of the intercepted arc, in terms of π, is
Arc length = (central/360)·2πr = (120/360)·2π(12) = 8π.
A circle has radius 10 and a central angle of 45°. The length of the intercepted arc, in terms of π, is
Arc length = (central/360)·2πr = (45/360)·2π(10) = 5π/2.
A circle has radius 4 and a central angle of 45°. The length of the intercepted arc, in terms of π, is
Arc length = (central/360)·2πr = (45/360)·2π(4) = 1π.
A circle has radius 8 and a central angle of 30°. The length of the intercepted arc, in terms of π, is
Arc length = (central/360)·2πr = (30/360)·2π(8) = 4π/3.
A circle has radius 12. The area of a sector with central angle 120° in terms of π is
Sector area = (central/360)·πr² = (120/360)·π(144) = 48π.
A circle has radius 9. The area of a sector with central angle 135° in terms of π is
Sector area = (central/360)·πr² = (135/360)·π(81) = 243π/8.
A circle has radius 6. The area of a sector with central angle 150° in terms of π is
Sector area = (central/360)·πr² = (150/360)·π(36) = 15π.
A circle has radius 12. The area of a sector with central angle 135° in terms of π is
Sector area = (central/360)·πr² = (135/360)·π(144) = 54π.
A tangent and a chord meet at the point of tangency, forming an angle that intercepts an arc of 68°. The angle measures
Tangent-chord angle = ½ intercepted arc = ½(68) = 34°.
The circle (x − -5)² + (y − -6)² = 64 has radius
r = √64 = 8.
Two chords intersect inside a circle. One chord is split into segments 15 and 8; the other into 2 and x. Find x.
Chord segments: 15·8 = 2·x → x = 120/2 = 60.
Two secants meet outside a circle, intercepting arcs of 280° and 90°. The angle formed measures
Exterior angle = ½(far arc − near arc) = ½(280−90) = 95°.
The distance between (-7, 1) and (0, 25) is
√((7)² + (24)²) = √625 = 25.
The distance between (-8, -4) and (12, 17) is
√((20)² + (21)²) = √841 = 29.
The distance between (-5, 3) and (3, 9) is
√((8)² + (6)²) = √100 = 10.
The distance between (-9, 2) and (-1, 8) is
√((8)² + (6)²) = √100 = 10.
The distance between (5, -5) and (14, 7) is
√((9)² + (12)²) = √225 = 15.
The midpoint of (3, -12) and (9, 2) is
Average the x's and the y's.
The midpoint of (-10, -10) and (-6, 12) is
Average the x's and the y's.
The midpoint of (-3, -5) and (-1, -9) is
Average the x's and the y's.
The midpoint of (-10, 9) and (-4, 7) is
Average the x's and the y's.
The midpoint of (-7, -6) and (-3, 10) is
Average the x's and the y's.
The slope of the line through (-1, 5) and (-4, 6) is
slope = Δy/Δx = (1)/(-3) = 1/-3.
The slope of the line through (8, 8) and (-7, -5) is
slope = Δy/Δx = (-13)/(-15) = -13/-15.
The slope of the line through (7, -5) and (1, 2) is
slope = Δy/Δx = (7)/(-6) = 7/-6.
The slope of the line through (-7, -2) and (-5, -1) is
slope = Δy/Δx = (1)/(2) = 1/2.
The slope of the line through (0, -2) and (-4, 0) is
slope = Δy/Δx = (2)/(-4) = 1/-2.
Point P divides the segment from A(3, -3) to B(8, 7) in the ratio 2:3. P is
P = A + 2/5(B−A) = (3,-3) + 2/5(5,10) = (5, 1).
Point P divides the segment from A(-2, -3) to B(13, 9) in the ratio 1:2. P is
P = A + 1/3(B−A) = (-2,-3) + 1/3(15,12) = (3, 1).
Point P divides the segment from A(-7, -1) to B(3, 14) in the ratio 1:4. P is
P = A + 1/5(B−A) = (-7,-1) + 1/5(10,15) = (-5, 2).
Point P divides the segment from A(-5, 3) to B(5, 18) in the ratio 1:4. P is
P = A + 1/5(B−A) = (-5,3) + 1/5(10,15) = (-3, 6).
Point P divides the segment from A(-9, -5) to B(0, 7) in the ratio 1:2. P is
P = A + 1/3(B−A) = (-9,-5) + 1/3(9,12) = (-6, -1).
A line contains the points (-2, -5) and (1, 0). An equation of a line PERPENDICULAR to it through (-5, -4) is
Original slope = 5/3. Perpendicular slope = −3/5. Through (-5,-4): y − -4 = -3/5(x − -5).
A line contains the points (0, 2) and (3, 7). An equation of a line PERPENDICULAR to it through (0, -3) is
Original slope = 5/3. Perpendicular slope = −3/5. Through (0,-3): y − -3 = -3/5(x − 0).
A line contains the points (3, 3) and (6, 7). An equation of a line PERPENDICULAR to it through (2, 1) is
Original slope = 4/3. Perpendicular slope = −3/4. Through (2,1): y − 1 = -3/4(x − 2).
A line contains the points (6, 4) and (8, 9). An equation of a line PERPENDICULAR to it through (-4, 4) is
Original slope = 5/2. Perpendicular slope = −2/5. Through (-4,4): y − 4 = -2/5(x − -4).
A line contains the points (0, -5) and (2, 0). An equation of a line PERPENDICULAR to it through (-6, -2) is
Original slope = 5/2. Perpendicular slope = −2/5. Through (-6,-2): y − -2 = -2/5(x − -6).
Quadrilateral ABCD has AB ∥ CD, AB ≅ CD, and diagonal AC ⊥ BD. It must be a
One pair of opposite sides parallel AND congruent makes it a parallelogram; perpendicular diagonals in a parallelogram make it a rhombus.
A circle has a diameter with endpoints (-2, 3) and (6, 9). The radius is
Diameter = √(8²+6²) = 10 → radius = 5.
A circle has a diameter with endpoints (-7, -7) and (-1, 1). The radius is
Diameter = √(6²+8²) = 10 → radius = 5.
A circle has a diameter with endpoints (-3, -4) and (3, 4). The radius is
Diameter = √(6²+8²) = 10 → radius = 5.
A circle has a diameter with endpoints (0, 0) and (6, 8). The radius is
Diameter = √(6²+8²) = 10 → radius = 5.
A circle has a diameter with endpoints (-1, -3) and (5, 5). The radius is
Diameter = √(6²+8²) = 10 → radius = 5.
The slope of the line through (0, -4) and (-7, 7) is
slope = Δy/Δx = (11)/(-7) = 11/-7.
The slope of the line through (-8, -7) and (0, -5) is
slope = Δy/Δx = (2)/(8) = 1/4.
The distance between (-1, 3) and (11, 12) is
√((12)² + (9)²) = √225 = 15.
The distance between (3, -8) and (12, 4) is
√((9)² + (12)²) = √225 = 15.
A line contains the points (6, 5) and (7, 7). An equation of a line PERPENDICULAR to it through (1, -1) is
Original slope = 2/1. Perpendicular slope = −1/2. Through (1,-1): y − -1 = -1/2(x − 1).
A line contains the points (6, 1) and (9, 5). An equation of a line PERPENDICULAR to it through (-3, 1) is
Original slope = 4/3. Perpendicular slope = −3/4. Through (-3,1): y − 1 = -3/4(x − -3).
A line contains the points (3, 6) and (7, 9). An equation of a line PERPENDICULAR to it through (-5, -6) is
Original slope = 3/4. Perpendicular slope = −4/3. Through (-5,-6): y − -6 = -4/3(x − -5).
The slope of the line through (7, -5) and (3, -8) is
slope = Δy/Δx = (-3)/(-4) = -3/-4.
A line contains the points (5, 2) and (6, 4). An equation of a line PERPENDICULAR to it through (4, 3) is
Original slope = 2/1. Perpendicular slope = −1/2. Through (4,3): y − 3 = -1/2(x − 4).
Reflecting (-3, -9) over the line y = x gives
Over y = x: swap the coordinates.
Reflecting (9, -9) over the line y = x gives
Over y = x: swap the coordinates.
Reflecting (-7, 4) over the line y = x gives
Over y = x: swap the coordinates.
Reflecting (-3, -1) over the line y = x gives
Over y = x: swap the coordinates.
Reflecting (10, 1) over the line y = x gives
Over y = x: swap the coordinates.
Rotating (5, -6) 90° counterclockwise about the origin gives
90° CCW: (x, y) → (−y, x).
Rotating (-5, -5) 90° counterclockwise about the origin gives
90° CCW: (x, y) → (−y, x).
Rotating (1, 6) 90° counterclockwise about the origin gives
90° CCW: (x, y) → (−y, x).
Rotating (10, -8) 90° counterclockwise about the origin gives
90° CCW: (x, y) → (−y, x).
Rotating (-3, 4) 90° counterclockwise about the origin gives
90° CCW: (x, y) → (−y, x).
Rotating (9, 1) 180° about the origin gives
180°: (x, y) → (−x, −y).
Rotating (-6, 3) 180° about the origin gives
180°: (x, y) → (−x, −y).
Rotating (-5, -8) 180° about the origin gives
180°: (x, y) → (−x, −y).
Rotating (10, 9) 180° about the origin gives
180°: (x, y) → (−x, −y).
Rotating (9, -4) 180° about the origin gives
180°: (x, y) → (−x, −y).
Point (6, 3) is translated by (x+-3, y+-5), then by (x+-1, y+6). The final image is
Apply both shifts: (6+-3+-1, 3+-5+6) = (2, 4).
Point (-6, -2) is translated by (x+-4, y+5), then by (x+-3, y+-5). The final image is
Apply both shifts: (-6+-4+-3, -2+5+-5) = (-13, -2).
Point (2, -5) is translated by (x+-6, y+-1), then by (x+-2, y+-6). The final image is
Apply both shifts: (2+-6+-2, -5+-1+-6) = (-6, -12).
Point (7, 6) is translated by (x+0, y+6), then by (x+5, y+0). The final image is
Apply both shifts: (7+0+5, 6+6+0) = (12, 12).
Point (-7, 1) is translated by (x+-1, y+6), then by (x+4, y+6). The final image is
Apply both shifts: (-7+-1+4, 1+6+6) = (-4, 13).
Dilating (-7, -9) by scale factor 4 centered at the origin gives
Multiply both coordinates by 4: (-7×4, -9×4) = (-28, -36).
Dilating (-5, -2) by scale factor 3 centered at the origin gives
Multiply both coordinates by 3: (-5×3, -2×3) = (-15, -6).
Dilating (0, 8) by scale factor 2 centered at the origin gives
Multiply both coordinates by 2: (0×2, 8×2) = (0, 16).
Dilating (2, -6) by scale factor 3 centered at the origin gives
Multiply both coordinates by 3: (2×3, -6×3) = (6, -18).
Dilating (-3, -2) by scale factor 3 centered at the origin gives
Multiply both coordinates by 3: (-3×3, -2×3) = (-9, -6).
Reflecting (-4, -5) over the x-axis gives
Over the x-axis: y negates.
Reflecting (-1, -6) over the x-axis gives
Over the x-axis: y negates.
Reflecting (10, 4) over the x-axis gives
Over the x-axis: y negates.
Reflecting (1, -9) over the y-axis gives
Over the y-axis: x negates.
Reflecting (7, 6) over the x-axis gives
Over the x-axis: y negates.
How many lines of reflectional symmetry does a isosceles triangle (non-equilateral) have?
A isosceles triangle (non-equilateral) has 1 line(s) of reflectional symmetry.
How many lines of reflectional symmetry does a square have?
A square has 4 line(s) of reflectional symmetry.
How many lines of reflectional symmetry does a regular pentagon have?
A regular pentagon has 5 line(s) of reflectional symmetry.
How many lines of reflectional symmetry does a regular octagon have?
A regular octagon has 8 line(s) of reflectional symmetry.
How many lines of reflectional symmetry does a regular hexagon have?
A regular hexagon has 6 line(s) of reflectional symmetry.
A regular 12-gon carries onto itself after a minimum rotation of
A regular n-gon maps onto itself every 360/n°: 360/12 = 30°.
A regular 8-gon carries onto itself after a minimum rotation of
A regular n-gon maps onto itself every 360/n°: 360/8 = 45°.
A regular 9-gon carries onto itself after a minimum rotation of
A regular n-gon maps onto itself every 360/n°: 360/9 = 40°.
A regular 10-gon carries onto itself after a minimum rotation of
A regular n-gon maps onto itself every 360/n°: 360/10 = 36°.
A regular 3-gon carries onto itself after a minimum rotation of
A regular n-gon maps onto itself every 360/n°: 360/3 = 120°.
A cylinder has radius 6 and height 4. Its volume is
V = πr²h = π(6²)(4) = 144π.
A cylinder has radius 12 and height 5. Its volume is
V = πr²h = π(12²)(5) = 720π.
A cylinder has radius 9 and height 8. Its volume is
V = πr²h = π(9²)(8) = 648π.
A cylinder has radius 5 and height 13. Its volume is
V = πr²h = π(5²)(13) = 325π.
A cylinder has radius 4 and height 15. Its volume is
V = πr²h = π(4²)(15) = 240π.
A sphere has radius 9. Its volume is
V = 4/3πr³ = 4/3π(9³) = 972π.
A sphere has radius 6. Its volume is
V = 4/3πr³ = 4/3π(6³) = 288π.
A sphere has radius 15. Its volume is
V = 4/3πr³ = 4/3π(15³) = 4500π.
A sphere has radius 12. Its volume is
V = 4/3πr³ = 4/3π(12³) = 2304π.
A rectangular prism measures 7 by 6 by 4 cm. If the material has density 0.5 g/cm³, its mass is
V = 7×6×4 = 168 cm³. Mass = volume × density = 168 × 0.5 = 84 g.
A rectangular prism measures 5 by 4 by 3 cm. If the material has density 1.2 g/cm³, its mass is
V = 5×4×3 = 60 cm³. Mass = volume × density = 60 × 1.2 = 72 g.
A rectangular prism measures 5 by 8 by 7 cm. If the material has density 1.2 g/cm³, its mass is
V = 5×8×7 = 280 cm³. Mass = volume × density = 280 × 1.2 = 336 g.
A rectangular prism measures 9 by 4 by 7 cm. If the material has density 2.5 g/cm³, its mass is
V = 9×4×7 = 252 cm³. Mass = volume × density = 252 × 2.5 = 630 g.
A rectangular prism measures 6 by 6 by 2 cm. If the material has density 2.5 g/cm³, its mass is
V = 6×6×2 = 72 cm³. Mass = volume × density = 72 × 2.5 = 180 g.
Two similar solids have a linear scale factor of 1:4. If the smaller solid's volume is 27, the larger's volume is
Volume ratio = (b/a)³ = (4/1)³. 27 × (4³/1³) = 1728.
Two similar solids have a linear scale factor of 1:5. If the smaller solid's volume is 125, the larger's volume is
Volume ratio = (b/a)³ = (5/1)³. 125 × (5³/1³) = 15625.
Two similar solids have a linear scale factor of 2:4. If the smaller solid's volume is 125, the larger's volume is
Volume ratio = (b/a)³ = (4/2)³. 125 × (4³/2³) = 1000.
Two similar solids have a linear scale factor of 1:5. If the smaller solid's volume is 27, the larger's volume is
Volume ratio = (b/a)³ = (5/1)³. 27 × (5³/1³) = 3375.
Two similar solids have a linear scale factor of 4:1. If the smaller solid's volume is 64, the larger's volume is
Volume ratio = (b/a)³ = (1/4)³. 64 × (1³/4³) = 1.
The cross-section of a cylinder, cut perpendicular to its base through the center is
Slicing a cylinder, cut perpendicular to its base through the center produces a rectangle.
The cross-section of a rectangular pyramid, cut parallel to its base is
Slicing a rectangular pyramid, cut parallel to its base produces a rectangle.
The cross-section of a cone, cut parallel to its base is
Slicing a cone, cut parallel to its base produces a circle.
The cross-section of a sphere, cut through its center is
Slicing a sphere, cut through its center produces a circle.
The cross-section of a cylinder, cut parallel to its base is
Slicing a cylinder, cut parallel to its base produces a circle.
A cylinder has radius 8 and height 12. Its total surface area is
SA = 2πr² + 2πrh = 2π(8²) + 2π(8)(12) = 320π.
A cylinder has radius 5 and height 12. Its total surface area is
SA = 2πr² + 2πrh = 2π(5²) + 2π(5)(12) = 170π.
A cylinder has radius 5 and height 3. Its total surface area is
SA = 2πr² + 2πrh = 2π(5²) + 2π(5)(3) = 80π.
A cylinder has radius 8 and height 9. Its total surface area is
SA = 2πr² + 2πrh = 2π(8²) + 2π(8)(9) = 272π.
A cylinder has radius 7 and height 15. Its total surface area is
SA = 2πr² + 2πrh = 2π(7²) + 2π(7)(15) = 308π.
A cylinder has radius 3 and height 4. Its total surface area is
SA = 2πr² + 2πrh = 2π(3²) + 2π(3)(4) = 42π.
A cylinder has radius 9 and height 6. Its volume is
V = πr²h = π(9²)(6) = 486π.
A cylinder has radius 6 and height 9. Its volume is
V = πr²h = π(6²)(9) = 324π.
A cylinder has radius 8 and height 11. Its total surface area is
SA = 2πr² + 2πrh = 2π(8²) + 2π(8)(11) = 304π.
A cylinder has radius 5 and height 11. Its volume is
V = πr²h = π(5²)(11) = 275π.
A rectangular prism measures 6 by 2 by 5 cm. If the material has density 1.2 g/cm³, its mass is
V = 6×2×5 = 60 cm³. Mass = volume × density = 60 × 1.2 = 72 g.
Two similar solids have a linear scale factor of 1:4. If the smaller solid's volume is 10, the larger's volume is
Volume ratio = (b/a)³ = (4/1)³. 10 × (4³/1³) = 640.
A rectangular prism measures 2 by 3 by 4 cm. If the material has density 0.5 g/cm³, its mass is
V = 2×3×4 = 24 cm³. Mass = volume × density = 24 × 0.5 = 12 g.
A cylinder has radius 4 and height 6. Its volume is
V = πr²h = π(4²)(6) = 96π.
A cylinder has radius 4 and height 5. Its total surface area is
SA = 2πr² + 2πrh = 2π(4²) + 2π(4)(5) = 72π.
A cylinder has radius 9 and height 9. Its volume is
V = πr²h = π(9²)(9) = 729π.
| Situation | Rule |
|---|---|
| Central angle | = intercepted arc |
| Inscribed angle | = ½ intercepted arc |
| Inscribed in a semicircle | = 90° (subtends a diameter) |
| Tangent–chord angle | = ½ intercepted arc |
| Cyclic quadrilateral | opposite angles are supplementary |
| Two chords meet inside | angle = ½(sum of arcs); (part)(part) = (part)(part) |
| Two secants meet outside | angle = ½(difference of arcs); (whole)(ext) = (whole)(ext) |
| Tangent + secant | tangent² = (whole secant)(external part) |
| Tangent & radius | meet at 90° at the point of tangency |
| ⊥ from center to a chord | bisects the chord and its arc |
| Triangle | Side Ratio | Rule |
|---|---|---|
| 45-45-90 | 1 : 1 : √2 | hypotenuse = leg · √2 |
| 30-60-90 | 1 : √3 : 2 | short leg : long leg : hypotenuse |
| Vertex location | Angle equals… |
|---|---|
| At the CENTER (central angle) | the whole intercepted arc |
| ON the circle (inscribed angle) | ½ the intercepted arc |
| INSIDE (two chords cross) | ½ the SUM of the two arcs |
| OUTSIDE (secants/tangents) | ½ the DIFFERENCE of the arcs |
| Inscribed in a semicircle | 90° (right angle) |
| Transformation | Rule (x, y) → | Size? |
|---|---|---|
| Translation | (x + a, y + b) | same |
| Reflect over x-axis | (x, −y) | same |
| Reflect over y-axis | (−x, y) | same |
| Reflect over y = x | (y, x) | same |
| Rotate 90° CCW | (−y, x) | same |
| Rotate 180° | (−x, −y) | same |
| Rotate 270° CCW | (y, −x) | same |
| Dilation (factor k) | (kx, ky) | CHANGES |
| Polygon | Sides (n) | Interior Sum (n−2)·180° | Each angle if regular |
|---|---|---|---|
| Triangle | 3 | 180° | 60° |
| Quadrilateral | 4 | 360° | 90° |
| Pentagon | 5 | 540° | 108° |
| Hexagon | 6 | 720° | 120° |
| Octagon | 8 | 1080° | 135° |
Exterior angles of ANY polygon always add to 360°. Each exterior of a regular n-gon = 360 ⁄ n.
| Shape | Key diagonal / side facts |
|---|---|
| Parallelogram | opp sides ∥ & ≅; diagonals bisect each other |
| Rectangle | parallelogram + 4 right angles + ≅ diagonals |
| Rhombus | parallelogram + 4 ≅ sides + ⊥ diagonals |
| Square | rectangle AND rhombus (all properties) |
| Isosceles Trapezoid | 1 pair ∥ sides; ≅ legs; ≅ diagonals; ≅ base angles |