← Angles and triangles lesson New set →

Angles and Triangles Worksheet for Maths Olympiad

Maths Olympiad topic 21: Angles and triangles · Set 841 · 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. Two vertically opposite angles add up to 90°. What is each of the other two angles? (a) 270° (b) 45° (c) 90° (d) 135°
  2. 2.Two straight lines cross. One of the angles is 40°. What is the angle next to it on the same straight line? (a) 40° (b) 140° (c) 50° (d) 320°
  3. 3.Two angles of a triangle are 70° and 95°. What is the third angle? (a) 110° (b) 85° (c) 165° (d) 15°
  4. 4.Two straight lines cross. One of the angles is 130°. What is the angle next to it on the same straight line? (a) 230° (b) 130° (c) 51° (d) 50°
  5. 5.Two straight lines cross. One of the angles is 50°. What is the angle next to it on the same straight line? (a) 310° (b) 40° (c) 130° (d) 50°
  6. 6.Two angles of a triangle are 35° and 20°. What is the third angle? (a) 145° (b) 160° (c) 125° (d) 55°
  7. 7.Two straight lines cross. One of the angles is 95°. What is the angle next to it on the same straight line? (a) 85° (b) 265° (c) 95° (d) 86°
  8. 8.Two angles of a triangle are 40° and 55°. What is the third angle? (a) 85° (b) 125° (c) 95° (d) 140°
  9. 9.Two angles of a triangle are 65° and 25°. What is the third angle? (a) 155° (b) 270° (c) 90° (d) 115°
  10. 10.Two angles of a triangle are 50° and 20°. What is the exterior angle at the third corner? (a) 130° (b) 160° (c) 70° (d) 110°
  11. 11.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°
  12. 12.Two angles of a triangle are 50° and 45°. What is the exterior angle at the third corner? (a) 95° (b) 85° (c) 130° (d) 135°
  13. 13.Two angles of a triangle are 70° and 75°. What is the exterior angle at the third corner? (a) 145° (b) 105° (c) 35° (d) 110°
  14. 14.Two angles of a triangle are 20° and 115°. What is the third angle? (a) 135° (b) 160° (c) 65° (d) 45°
  15. 15.Two angles of a triangle are 25° and 30°. What is the exterior angle at the third corner? (a) 55° (b) 150° (c) 155° (d) 125°
  16. 16.Two straight lines cross. One of the angles is 140°. What is the angle next to it on the same straight line? (a) 220° (b) 40° (c) 41° (d) 140°
  17. 17.Two angles of a triangle are 30° and 75°. What is the exterior angle at the third corner? (a) 105° (b) 255° (c) 150° (d) 75°
  18. 18.Two angles of a triangle are 20° and 65°. What is the exterior angle at the third corner? (a) 95° (b) 115° (c) 160° (d) 85°
  19. 19.Two angles of a triangle are 45° and 100°. What is the exterior angle at the third corner? (a) 135° (b) 145° (c) 35° (d) 80°
  20. 20.Two angles of a triangle are 80° and 20°. What is the third angle? (a) 80° (b) 100° (c) 160° (d) 260°
  21. 21.Two straight lines cross. One of the angles is 170°. What is the angle next to it on the same straight line? (a) 190° (b) 11° (c) 10° (d) 170°
  22. 22.Two straight lines cross. Two vertically opposite angles add up to 150°. What is each of the other two angles? (a) 75° (b) 210° (c) 30° (d) 105°
  23. 23.Two straight lines cross. Two vertically opposite angles add up to 320°. What is each of the other two angles? (a) 40° (b) 160° (c) 21° (d) 20°
  24. 24.Two angles of a triangle are 40° and 50°. What is the third angle? (a) 130° (b) 90° (c) 270° (d) 140°
  25. 25.Two angles of a triangle are 35° and 55°. What is the exterior angle at the third corner? (a) 145° (b) 270° (c) 125° (d) 90°
  26. 26.In an isosceles triangle, the two equal angles are 30° each. What is the third angle? (a) 150° (b) 60° (c) 120° (d) 30°
  27. 27.Two angles of a triangle are 65° and 75°. What is the third angle? (a) 140° (b) 105° (c) 115° (d) 40°
  28. 28.In an isosceles triangle, the angle between the two equal sides is 150°. What is each of the other two angles? (a) 150° (b) 15° (c) 30° (d) 25°
  29. 29.Two angles of a triangle are 75° and 40°. What is the exterior angle at the third corner? (a) 140° (b) 105° (c) 65° (d) 115°
  30. 30.In an isosceles triangle, the two equal angles are 40° each. What is the third angle? (a) 50° (b) 140° (c) 40° (d) 100°
  31. 31.Two straight lines cross. Two vertically opposite angles add up to 280°. What is each of the other two angles? (a) 41° (b) 80° (c) 40° (d) 140°
  32. 32.Two angles of a triangle are 75° and 40°. What is the third angle? (a) 65° (b) 115° (c) 105° (d) 140°
  33. 33.Two angles of a triangle are 50° and 50°. What is the exterior angle at the third corner? (a) 260° (b) 100° (c) 130° (d) 80°
  34. 34.Two angles of a triangle are 60° and 55°. What is the third angle? (a) 125° (b) 120° (c) 65° (d) 115°
  35. 35.Two angles of a triangle are 20° and 100°. What is the exterior angle at the third corner? (a) 160° (b) 60° (c) 80° (d) 120°
  36. 36.Two angles of a triangle are 60° and 25°. What is the exterior angle at the third corner? (a) 95° (b) 155° (c) 120° (d) 85°
  37. 37.Two angles of a triangle are 30° and 75°. What is the third angle? (a) 255° (b) 105° (c) 75° (d) 150°
  38. 38.Two angles of a triangle are 50° and 55°. What is the third angle? (a) 75° (b) 105° (c) 130° (d) 125°
  39. 39.In an isosceles triangle, the angle between the two equal sides is 100°. What is each of the other two angles? (a) 100° (b) 40° (c) 80° (d) 50°
  40. 40.Two angles of a triangle are 80° and 30°. What is the exterior angle at the third corner? (a) 100° (b) 70° (c) 150° (d) 110°

Answer key

  1. 135°
  2. 140°
  3. 15°
  4. 50°
  5. 130°
  6. 125°
  7. 85°
  8. 85°
  9. 90°
  10. 70°
  11. 70°
  12. 95°
  13. 145°
  14. 45°
  15. 55°
  16. 40°
  17. 105°
  18. 85°
  19. 145°
  20. 80°
  21. 10°
  22. 105°
  23. 20°
  24. 90°
  25. 90°
  26. 120°
  27. 40°
  28. 15°
  29. 115°
  30. 100°
  31. 40°
  32. 65°
  33. 100°
  34. 65°
  35. 120°
  36. 85°
  37. 75°
  38. 75°
  39. 40°
  40. 110°

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