Angles and Triangles Worksheet for Maths Olympiad

Maths Olympiad topic 21: Angles and triangles · Set 31 · 40 questions

How to solve it (180 is the magic number): The three angles of a triangle add up to 180°. An exterior angle equals the sum of the two interior angles opposite it. An isosceles triangle has two equal angles, opposite its two equal sides. Angles on a straight line add up to 180°; vertically opposite angles are equal.

1. 1.Two angles of a triangle are 35° and 115°. What is the exterior angle at the third corner? (a) 150° (b) 30° (c) 65° (d) 145°
2. 2.Two angles of a triangle are 20° and 80°. What is the exterior angle at the third corner? (a) 80° (b) 100° (c) 160° (d) 260°
3. 3.Two angles of a triangle are 70° and 80°. What is the exterior angle at the third corner? (a) 30° (b) 150° (c) 100° (d) 110°
4. 4.Two angles of a triangle are 45° and 45°. What is the third angle? (a) 90° (b) 270° (c) 135° (d) 91°
5. 5.Two angles of a triangle are 50° and 75°. What is the exterior angle at the third corner? (a) 55° (b) 105° (c) 130° (d) 125°
6. 6.Two angles of a triangle are 45° and 90°. What is the third angle? (a) 135° (b) 90° (c) 45° (d) 225°
7. 7.Two straight lines cross. One of the angles is 105°. What is the angle next to it on the same straight line? (a) 75° (b) 76° (c) 105° (d) 255°
8. 8.Two straight lines cross. Two vertically opposite angles add up to 50°. What is each of the other two angles? (a) 130° (b) 310° (c) 155° (d) 25°
9. 9.Two angles of a triangle are 30° and 40°. What is the exterior angle at the third corner? (a) 110° (b) 140° (c) 70° (d) 150°
10. 10.In an isosceles triangle, the angle between the two equal sides is 150°. What is each of the other two angles? (a) 15° (b) 25° (c) 150° (d) 30°
11. 11.Two straight lines cross. Two vertically opposite angles add up to 200°. What is each of the other two angles? (a) 100° (b) 160° (c) 81° (d) 80°
12. 12.Two straight lines cross. One of the angles is 155°. What is the angle next to it on the same straight line? (a) 26° (b) 25° (c) 205° (d) 155°
13. 13.Two angles of a triangle are 30° and 120°. What is the exterior angle at the third corner? (a) 210° (b) 60° (c) 30° (d) 150°
14. 14.In an isosceles triangle, the two equal angles are 30° each. What is the third angle? (a) 120° (b) 150° (c) 60° (d) 30°
15. 15.Two straight lines cross. One of the angles is 170°. What is the angle next to it on the same straight line? (a) 170° (b) 11° (c) 10° (d) 190°
16. 16.In an isosceles triangle, the two equal angles are 55° each. What is the third angle? (a) 35° (b) 55° (c) 125° (d) 70°
17. 17.Two straight lines cross. Two vertically opposite angles add up to 60°. What is each of the other two angles? (a) 150° (b) 300° (c) 120° (d) 30°
18. 18.Two angles of a triangle are 20° and 60°. What is the third angle? (a) 80° (b) 160° (c) 120° (d) 100°
19. 19.Two angles of a triangle are 40° and 75°. What is the exterior angle at the third corner? (a) 65° (b) 105° (c) 115° (d) 140°
20. 20.Two straight lines cross. Two vertically opposite angles add up to 40°. What is each of the other two angles? (a) 140° (b) 320° (c) 160° (d) 20°
21. 21.In an isosceles triangle, the angle between the two equal sides is 20°. What is each of the other two angles? (a) 160° (b) 20° (c) 70° (d) 80°
22. 22.Two angles of a triangle are 45° and 40°. What is the exterior angle at the third corner? (a) 85° (b) 140° (c) 135° (d) 95°
23. 23.Two straight lines cross. Two vertically opposite angles add up to 190°. What is each of the other two angles? (a) 170° (b) 86° (c) 95° (d) 85°
24. 24.Two angles of a triangle are 35° and 20°. What is the exterior angle at the third corner? (a) 55° (b) 125° (c) 160° (d) 145°
25. 25.In an isosceles triangle, the angle between the two equal sides is 50°. What is each of the other two angles? (a) 50° (b) 65° (c) 130° (d) 40°
26. 26.Two angles of a triangle are 70° and 35°. What is the third angle? (a) 145° (b) 110° (c) 105° (d) 75°
27. 27.Two angles of a triangle are 35° and 75°. What is the exterior angle at the third corner? (a) 70° (b) 110° (c) 105° (d) 145°
28. 28.Two angles of a triangle are 45° and 95°. What is the third angle? (a) 135° (b) 85° (c) 140° (d) 40°
29. 29.Two straight lines cross. Two vertically opposite angles add up to 320°. What is each of the other two angles? (a) 21° (b) 40° (c) 160° (d) 20°
30. 30.Two angles of a triangle are 20° and 35°. What is the exterior angle at the third corner? (a) 160° (b) 125° (c) 55° (d) 145°
31. 31.Two angles of a triangle are 20° and 125°. What is the exterior angle at the third corner? (a) 35° (b) 160° (c) 55° (d) 145°
32. 32.Two angles of a triangle are 70° and 70°. What is the third angle? (a) 220° (b) 140° (c) 40° (d) 110°
33. 33.Two angles of a triangle are 25° and 120°. What is the third angle? (a) 60° (b) 145° (c) 155° (d) 35°
34. 34.In an isosceles triangle, the angle between the two equal sides is 110°. What is each of the other two angles? (a) 45° (b) 35° (c) 70° (d) 110°
35. 35.Two straight lines cross. One of the angles is 140°. What is the angle next to it on the same straight line? (a) 41° (b) 40° (c) 220° (d) 140°
36. 36.Two angles of a triangle are 25° and 140°. What is the third angle? (a) 15° (b) 40° (c) 155° (d) 165°
37. 37.Two angles of a triangle are 45° and 65°. What is the exterior angle at the third corner? (a) 70° (b) 135° (c) 115° (d) 110°
38. 38.Two angles of a triangle are 70° and 90°. What is the third angle? (a) 160° (b) 90° (c) 110° (d) 20°
39. 39.Two angles of a triangle are 30° and 20°. What is the third angle? (a) 130° (b) 160° (c) 150° (d) 50°
40. 40.Two angles of a triangle are 20° and 110°. What is the exterior angle at the third corner? (a) 50° (b) 130° (c) 160° (d) 70°

Free maths olympiad lessons, practice and worksheets at talentjr.in/maths-olympiad