L28 · Unknown angle measures

1. 1.

   Two angles are complementary. One measures 36°. Find the other.

   Answer. 54°

   Complementary angles sum to 90°, so 90 − 36 = 54.

2. 2.

   Two angles are complementary. One measures 68°. Find the other.

   Answer. 22°

   Complementary angles sum to 90°, so 90 − 68 = 22.

3. 3.

   Two angles are supplementary. One measures 99°. Find the other.

   Answer. 81°

   Supplementary angles sum to 180°, so 180 − 99 = 81.

4. 4.

   Two angles are complementary. One measures 56°. Find the other.

   Answer. 34°

   Complementary angles sum to 90°, so 90 − 56 = 34.

5. 5.

   Two angles are complementary. One measures 64°. Find the other. Then Sam needs 3 of that amount. What is the total they need?

   Answer. 78°

   Complementary angles sum to 90°, so 90 − 64 = 26. Then multiply by 3: 78°.

6. 6.

   Two angles are complementary. One measures 43°. Find the other. Then Malik needs 5 of that amount. What is the total they need?

   Answer. 235°

   Complementary angles sum to 90°, so 90 − 43 = 47. Then multiply by 5: 235°.

7. 7.

   Two angles are supplementary. One measures 108°. Find the other. Then Nora needs 5 of that amount. What is the total they need?

   Answer. 360°

   Supplementary angles sum to 180°, so 180 − 108 = 72. Then multiply by 5: 360°.

8. 8.

   Two angles are supplementary. One measures 64°. Find the other. Then Ava needs 2 of that amount. What is the total they need?

   Answer. 232°

   Supplementary angles sum to 180°, so 180 − 64 = 116. Then multiply by 2: 232°.

9. 9.

   Two angles are supplementary. One measures 91°. Find the other. Then Priya needs 3 of that amount. What is the total they need?

   Answer. 267°

   Supplementary angles sum to 180°, so 180 − 91 = 89. Then multiply by 3: 267°.

10. 10.

    Two angles are supplementary. One measures 96°. Find the other. Then Ava needs 5 of that amount. What is the total they need?

    Answer. 420°

    Supplementary angles sum to 180°, so 180 − 96 = 84. Then multiply by 5: 420°.

11. 11.

    Think

    Nora tried this problem:
    Two angles are complementary. One measures 51°. Find the other.
    Nora wrote 78°. That is not correct. What is the right answer?

    Answer. 39°

    Nora’s answer 78° is off. Complementary angles sum to 90°, so 90 − 51 = 39.

12. 12.

    Think

    Mei tried this problem:
    Two angles are supplementary. One measures 87°. Find the other.
    Mei wrote 186°. That is not correct. What is the right answer?

    Answer. 93°

    Mei’s answer 186° is off. Supplementary angles sum to 180°, so 180 − 87 = 93.

Original extra practice. Keys are computed from the items, not guessed.