7th grade · Math · Unit 15 of 17

Angle Relationships

Complementary, supplementary, vertical

What your child practices

Using complementary, supplementary, vertical and adjacent angles to find a missing angle, sometimes with a simple equation.

California Content Standards learning standard: 7.G.5 · using supplementary, complementary, vertical and adjacent angles to find unknown angles

How we explain it

Children can open this short lesson before they practice.

Complementary angles add to 90°. Supplementary angles add to 180°.
Vertical angles (opposite when lines cross) are equal.
Write an equation and solve for the missing angle.

Example: Two angles are supplementary. One is 65°. What is the other? 180 − 65 = 115. Answer: 115°

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

Question 1
Two angles are supplementary. One is x and the other is 5x. What is x?
- 150°
- 40°
- 36°
- 30°
Question 2
Three angles sit side by side on a straight line. Two of them are 27° and 23°. What is the third?
- 67°
- 50°
- 130°
- 310°
Question 3
Two angles are complementary. One is 53°. What is the other?
- 53°
- 37°
- 34°
- 127°
Question 4
Two lines cross. One angle is 45°. What is the angle vertically opposite to it?
- 45°
- 135°
- 315°
- 44°
Question 5
Two angles are supplementary. One is x and the other is 5x. What is x?
- 30°
- 150°
- 36°
- 40°
Question 6
Two lines cross. One angle is 131°. What is the angle next to it on the same line?
- 50°
- 49°
- 131°
- 229°