What angle relationships do students need?

Angles on a straight line sum to 180°, angles in a triangle sum to 180°, and angles around a point sum to 360°.

Can a missing angle be larger than 90°?

Yes. Missing angles can be obtuse (90°–180°) or even reflex (180°–360°) depending on the diagram.

Beginners: one unknown on a straight line. Intermediate: triangles. Advanced: multi-step diagrams combining rules.

Generate unlimited practice problems with a guaranteed-correct answer key.

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Problems

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Max angle

150

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Answer Key

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Name:Date:Class:

1.Find the missing angle:

57° + 1° + ? = 180°

2.Find the missing angle:

19° + 42° + ? = 180°

3.Find the missing angle:

29° + 105° + ? = 180°

4.Find the missing angle:

12° + 105° + ? = 180°

5.Find the missing angle:

96° + 40° + ? = 180°

6.Find the missing angle:

61° + 7° + ? = 180°

7.Find the missing angle:

45° + 2° + ? = 180°

8.Find the missing angle:

21° + 10° + ? = 180°

9.Find the missing angle:

124° + 46° + ? = 180°

10.Find the missing angle:

62° + 63° + ? = 180°

11.Find the missing angle:

7° + 90° + ? = 180°

12.Find the missing angle:

13° + 75° + ? = 180°

13.Find the missing angle:

72° + 12° + ? = 180°

14.Find the missing angle:

49° + 78° + ? = 180°

15.Find the missing angle:

141° + 28° + ? = 180°

16.Find the missing angle:

63° + 26° + ? = 180°

17.Find the missing angle:

29° + 133° + ? = 180°

18.Find the missing angle:

105° + 35° + ? = 180°

19.Find the missing angle:

43° + 38° + ? = 180°

20.Find the missing angle:

5° + 48° + ? = 180°

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Problem: A triangle has angles 47° and 68°. Find the third angle.

Answer: 65°