← Angles and triangles lesson New set →

Angles and Triangles Worksheet for Maths Olympiad

Maths Olympiad topic 21: Angles and triangles · Set 808 · 40 questions
TalentJR

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.

NameDateTime takenScore ___ / 40
  1. 1.Two straight lines cross. One of the angles is 95°. What is the angle next to it on the same straight line? (a) 86° (b) 85° (c) 265° (d) 95°
  2. 2.Two angles of a triangle are 40° and 90°. What is the third angle? (a) 140° (b) 50° (c) 130° (d) 90°
  3. 3.Two straight lines cross. One of the angles is 160°. What is the angle next to it on the same straight line? (a) 160° (b) 20° (c) 200° (d) 21°
  4. 4.Two straight lines cross. Two vertically opposite angles add up to 340°. What is each of the other two angles? (a) 20° (b) 11° (c) 10° (d) 170°
  5. 5.In an isosceles triangle, the angle between the two equal sides is 40°. What is each of the other two angles? (a) 140° (b) 50° (c) 70° (d) 40°
  6. 6.In an isosceles triangle, the angle between the two equal sides is 160°. What is each of the other two angles? (a) 20° (b) 11° (c) 160° (d) 10°
  7. 7.Two angles of a triangle are 70° and 80°. What is the third angle? (a) 150° (b) 100° (c) 110° (d) 30°
  8. 8.Two angles of a triangle are 30° and 65°. What is the exterior angle at the third corner? (a) 85° (b) 115° (c) 150° (d) 95°
  9. 9.Two straight lines cross. One of the angles is 70°. What is the angle next to it on the same straight line? (a) 110° (b) 70° (c) 290° (d) 20°
  10. 10.Two angles of a triangle are 25° and 50°. What is the third angle? (a) 75° (b) 155° (c) 130° (d) 105°
  11. 11.Two straight lines cross. One of the angles is 20°. What is the angle next to it on the same straight line? (a) 340° (b) 70° (c) 20° (d) 160°
  12. 12.Two angles of a triangle are 60° and 95°. What is the third angle? (a) 85° (b) 155° (c) 120° (d) 25°
  13. 13.Two straight lines cross. One of the angles is 40°. What is the angle next to it on the same straight line? (a) 320° (b) 140° (c) 50° (d) 40°
  14. 14.Two angles of a triangle are 75° and 75°. What is the third angle? (a) 105° (b) 30° (c) 150° (d) 210°
  15. 15.Two angles of a triangle are 65° and 45°. What is the exterior angle at the third corner? (a) 115° (b) 70° (c) 135° (d) 110°
  16. 16.In an isosceles triangle, the two equal angles are 45° each. What is the third angle? (a) 91° (b) 45° (c) 135° (d) 90°
  17. 17.Two angles of a triangle are 50° and 65°. What is the third angle? (a) 65° (b) 130° (c) 245° (d) 115°
  18. 18.Two angles of a triangle are 80° and 25°. What is the exterior angle at the third corner? (a) 105° (b) 155° (c) 100° (d) 75°
  19. 19.Two angles of a triangle are 20° and 25°. What is the exterior angle at the third corner? (a) 155° (b) 135° (c) 160° (d) 45°
  20. 20.Two angles of a triangle are 25° and 60°. What is the third angle? (a) 95° (b) 120° (c) 155° (d) 85°
  21. 21.Two straight lines cross. Two vertically opposite angles add up to 310°. What is each of the other two angles? (a) 155° (b) 50° (c) 26° (d) 25°
  22. 22.In an isosceles triangle, the angle between the two equal sides is 150°. What is each of the other two angles? (a) 15° (b) 30° (c) 25° (d) 150°
  23. 23.Two angles of a triangle are 20° and 30°. What is the third angle? (a) 50° (b) 130° (c) 160° (d) 150°
  24. 24.In an isosceles triangle, the angle between the two equal sides is 130°. What is each of the other two angles? (a) 25° (b) 35° (c) 130° (d) 50°
  25. 25.Two angles of a triangle are 60° and 90°. What is the third angle? (a) 30° (b) 90° (c) 150° (d) 120°
  26. 26.Two angles of a triangle are 75° and 80°. What is the third angle? (a) 155° (b) 25° (c) 100° (d) 105°
  27. 27.Two straight lines cross. Two vertically opposite angles add up to 240°. What is each of the other two angles? (a) 120° (b) 61° (c) 59° (d) 60°
  28. 28.Two angles of a triangle are 30° and 30°. What is the third angle? (a) 60° (b) 300° (c) 150° (d) 120°
  29. 29.Two angles of a triangle are 70° and 30°. What is the third angle? (a) 150° (b) 80° (c) 100° (d) 110°
  30. 30.Two angles of a triangle are 70° and 20°. What is the third angle? (a) 160° (b) 110° (c) 270° (d) 90°
  31. 31.Two angles of a triangle are 25° and 110°. What is the third angle? (a) 155° (b) 45° (c) 70° (d) 135°
  32. 32.Two straight lines cross. One of the angles is 105°. What is the angle next to it on the same straight line? (a) 105° (b) 255° (c) 75° (d) 76°
  33. 33.Two angles of a triangle are 20° and 20°. What is the exterior angle at the third corner? (a) 320° (b) 140° (c) 40° (d) 160°
  34. 34.Two angles of a triangle are 20° and 45°. What is the third angle? (a) 135° (b) 115° (c) 160° (d) 65°
  35. 35.Two angles of a triangle are 35° and 85°. What is the exterior angle at the third corner? (a) 60° (b) 145° (c) 95° (d) 120°
  36. 36.Two angles of a triangle are 45° and 95°. What is the third angle? (a) 85° (b) 140° (c) 135° (d) 40°
  37. 37.Two angles of a triangle are 20° and 85°. What is the exterior angle at the third corner? (a) 105° (b) 95° (c) 160° (d) 75°
  38. 38.Two straight lines cross. One of the angles is 80°. What is the angle next to it on the same straight line? (a) 10° (b) 280° (c) 80° (d) 100°
  39. 39.Two straight lines cross. Two vertically opposite angles add up to 160°. What is each of the other two angles? (a) 200° (b) 100° (c) 80° (d) 20°
  40. 40.Two angles of a triangle are 55° and 65°. What is the exterior angle at the third corner? (a) 60° (b) 115° (c) 120° (d) 125°

Answer key

  1. 85°
  2. 50°
  3. 20°
  4. 10°
  5. 70°
  6. 10°
  7. 30°
  8. 95°
  9. 110°
  10. 105°
  11. 160°
  12. 25°
  13. 140°
  14. 30°
  15. 110°
  16. 90°
  17. 65°
  18. 105°
  19. 45°
  20. 95°
  21. 25°
  22. 15°
  23. 130°
  24. 25°
  25. 30°
  26. 25°
  27. 60°
  28. 120°
  29. 80°
  30. 90°
  31. 45°
  32. 75°
  33. 40°
  34. 115°
  35. 120°
  36. 40°
  37. 105°
  38. 100°
  39. 100°
  40. 120°

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