← Angles and triangles lesson New set →

Angles and Triangles Worksheet for Maths Olympiad

Maths Olympiad topic 21: Angles and triangles · Set 340 · 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 angles of a triangle are 75° and 35°. What is the exterior angle at the third corner? (a) 70° (b) 105° (c) 145° (d) 110°
  2. 2.Two angles of a triangle are 35° and 120°. What is the third angle? (a) 25° (b) 60° (c) 155° (d) 145°
  3. 3.Two straight lines cross. One of the angles is 130°. What is the angle next to it on the same straight line? (a) 130° (b) 50° (c) 230° (d) 51°
  4. 4.In an isosceles triangle, the two equal angles are 65° each. What is the third angle? (a) 115° (b) 65° (c) 50° (d) 25°
  5. 5.In an isosceles triangle, the angle between the two equal sides is 160°. What is each of the other two angles? (a) 20° (b) 160° (c) 11° (d) 10°
  6. 6.Two angles of a triangle are 55° and 70°. What is the third angle? (a) 125° (b) 110° (c) 55° (d) 235°
  7. 7.Two straight lines cross. Two vertically opposite angles add up to 80°. What is each of the other two angles? (a) 100° (b) 140° (c) 280° (d) 40°
  8. 8.Two angles of a triangle are 25° and 70°. What is the third angle? (a) 155° (b) 110° (c) 85° (d) 95°
  9. 9.Two angles of a triangle are 30° and 40°. What is the third angle? (a) 110° (b) 150° (c) 140° (d) 70°
  10. 10.Two angles of a triangle are 20° and 45°. What is the exterior angle at the third corner? (a) 65° (b) 135° (c) 115° (d) 160°
  11. 11.Two angles of a triangle are 55° and 40°. What is the third angle? (a) 95° (b) 85° (c) 125° (d) 140°
  12. 12.In an isosceles triangle, the angle between the two equal sides is 120°. What is each of the other two angles? (a) 60° (b) 120° (c) 40° (d) 30°
  13. 13.Two straight lines cross. One of the angles is 100°. What is the angle next to it on the same straight line? (a) 100° (b) 260° (c) 81° (d) 80°
  14. 14.Two straight lines cross. Two vertically opposite angles add up to 250°. What is each of the other two angles? (a) 125° (b) 55° (c) 110° (d) 56°
  15. 15.Two angles of a triangle are 45° and 50°. What is the exterior angle at the third corner? (a) 95° (b) 85° (c) 130° (d) 135°
  16. 16.Two angles of a triangle are 25° and 40°. What is the exterior angle at the third corner? (a) 115° (b) 155° (c) 65° (d) 140°
  17. 17.Two straight lines cross. Two vertically opposite angles add up to 60°. What is each of the other two angles? (a) 30° (b) 120° (c) 300° (d) 150°
  18. 18.Two angles of a triangle are 70° and 65°. What is the third angle? (a) 135° (b) 110° (c) 115° (d) 45°
  19. 19.Two angles of a triangle are 65° and 30°. What is the third angle? (a) 150° (b) 95° (c) 115° (d) 85°
  20. 20.Two angles of a triangle are 20° and 70°. What is the exterior angle at the third corner? (a) 110° (b) 270° (c) 160° (d) 90°
  21. 21.In an isosceles triangle, the angle between the two equal sides is 140°. What is each of the other two angles? (a) 40° (b) 20° (c) 140° (d) 30°
  22. 22.In an isosceles triangle, the two equal angles are 80° each. What is the third angle? (a) 80° (b) 100° (c) 20° (d) 10°
  23. 23.Two angles of a triangle are 80° and 25°. What is the exterior angle at the third corner? (a) 75° (b) 155° (c) 105° (d) 100°
  24. 24.Two angles of a triangle are 20° and 70°. What is the third angle? (a) 270° (b) 160° (c) 90° (d) 110°
  25. 25.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°
  26. 26.Two angles of a triangle are 55° and 95°. What is the exterior angle at the third corner? (a) 85° (b) 125° (c) 150° (d) 30°
  27. 27.Two angles of a triangle are 35° and 55°. What is the exterior angle at the third corner? (a) 90° (b) 125° (c) 270° (d) 145°
  28. 28.In an isosceles triangle, the two equal angles are 30° each. What is the third angle? (a) 120° (b) 30° (c) 150° (d) 60°
  29. 29.Two angles of a triangle are 45° and 100°. What is the third angle? (a) 135° (b) 80° (c) 35° (d) 145°
  30. 30.Two angles of a triangle are 70° and 35°. What is the exterior angle at the third corner? (a) 145° (b) 105° (c) 110° (d) 75°
  31. 31.Two straight lines cross. One of the angles is 50°. What is the angle next to it on the same straight line? (a) 50° (b) 40° (c) 310° (d) 130°
  32. 32.Two straight lines cross. One of the angles is 150°. What is the angle next to it on the same straight line? (a) 30° (b) 210° (c) 31° (d) 150°
  33. 33.Two straight lines cross. One of the angles is 165°. What is the angle next to it on the same straight line? (a) 195° (b) 16° (c) 165° (d) 15°
  34. 34.Two angles of a triangle are 35° and 20°. What is the third angle? (a) 125° (b) 145° (c) 55° (d) 160°
  35. 35.Two straight lines cross. Two vertically opposite angles add up to 150°. What is each of the other two angles? (a) 105° (b) 210° (c) 75° (d) 30°
  36. 36.Two angles of a triangle are 30° and 100°. What is the third angle? (a) 80° (b) 50° (c) 130° (d) 150°
  37. 37.Two straight lines cross. Two vertically opposite angles add up to 170°. What is each of the other two angles? (a) 190° (b) 95° (c) 10° (d) 85°
  38. 38.Two angles of a triangle are 35° and 60°. What is the exterior angle at the third corner? (a) 145° (b) 85° (c) 95° (d) 120°
  39. 39.Two angles of a triangle are 35° and 135°. What is the third angle? (a) 145° (b) 45° (c) 170° (d) 10°
  40. 40.Two angles of a triangle are 30° and 35°. What is the exterior angle at the third corner? (a) 65° (b) 150° (c) 115° (d) 145°

Answer key

  1. 110°
  2. 25°
  3. 50°
  4. 50°
  5. 10°
  6. 55°
  7. 140°
  8. 85°
  9. 110°
  10. 65°
  11. 85°
  12. 30°
  13. 80°
  14. 55°
  15. 95°
  16. 65°
  17. 150°
  18. 45°
  19. 85°
  20. 90°
  21. 20°
  22. 20°
  23. 105°
  24. 90°
  25. 85°
  26. 150°
  27. 90°
  28. 120°
  29. 35°
  30. 105°
  31. 130°
  32. 30°
  33. 15°
  34. 125°
  35. 105°
  36. 50°
  37. 95°
  38. 95°
  39. 10°
  40. 65°

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