Subscribe

7th grade · Math · Unit 20 of 22

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.

Texas Essential Knowledge and Skills (TEKS) teks student expectation: 7.11(C) · writing and solving equations with angle relationships

How we explain it

Children can open this short lesson before they practice.

  1. Complementary angles add to 90°. Supplementary angles add to 180°.
  2. Vertical angles (opposite when lines cross) are equal.
  3. 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°

Angle Relationships in Texas

In the Texas Essential Knowledge and Skills (TEKS), this is unit 20 of 22 in 7th grade Math, after Algebra Moves and before Tips, Discounts & Interest.

Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.

Source: Texas Education Agency (TEA)

Sample questions

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

  1. Question 1

    Three angles sit side by side on a straight line. Two of them are 37° and 21°. What is the third?

    • 58°
    • 122°
    • 302°
    • 69°

  2. Question 2

    Two angles are complementary. One is 62°. What is the other?

    • 28°
    • 118°
    • 62°
    • 30°

  3. Question 3

    Two lines cross. One angle is 147°. What is the angle vertically opposite to it?

    • 147°
    • 149°
    • 33°
    • 213°

  4. Question 4

    Two angles are complementary. One is x and the other is 5x. What is x?

    • 25°
    • 18°
    • 15°
    • 75°

  5. Question 5

    Two angles are supplementary. One is x and the other is 4x. What is x?

    • 45°
    • 36°
    • 46°
    • 144°

  6. Question 6

    Two lines cross. One angle is 126°. What is the angle vertically opposite to it?

    • 234°
    • 127°
    • 126°
    • 54°

More 7th grade