← Angles and triangles lesson New set →

Angles and Triangles Worksheet for Maths Olympiad

Maths Olympiad topic 21: Angles and triangles · Set 816 · 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 190°. What is each of the other two angles? (a) 95° (b) 85° (c) 170° (d) 86°
  2. 2.Two angles of a triangle are 25° and 45°. What is the exterior angle at the third corner? (a) 70° (b) 155° (c) 135° (d) 110°
  3. 3.Two angles of a triangle are 55° and 35°. What is the third angle? (a) 90° (b) 125° (c) 270° (d) 145°
  4. 4.Two angles of a triangle are 45° and 40°. What is the third angle? (a) 140° (b) 85° (c) 135° (d) 95°
  5. 5.Two angles of a triangle are 65° and 40°. What is the exterior angle at the third corner? (a) 105° (b) 140° (c) 115° (d) 75°
  6. 6.Two angles of a triangle are 20° and 65°. What is the third angle? (a) 95° (b) 160° (c) 115° (d) 85°
  7. 7.In an isosceles triangle, the angle between the two equal sides is 20°. What is each of the other two angles? (a) 160° (b) 70° (c) 80° (d) 20°
  8. 8.Two straight lines cross. One of the angles is 50°. What is the angle next to it on the same straight line? (a) 40° (b) 310° (c) 50° (d) 130°
  9. 9.In an isosceles triangle, the two equal angles are 65° each. What is the third angle? (a) 65° (b) 115° (c) 50° (d) 25°
  10. 10.Two angles of a triangle are 70° and 100°. What is the third angle? (a) 110° (b) 10° (c) 80° (d) 170°
  11. 11.Two straight lines cross. Two vertically opposite angles add up to 70°. What is each of the other two angles? (a) 145° (b) 110° (c) 290° (d) 35°
  12. 12.Two angles of a triangle are 55° and 45°. What is the exterior angle at the third corner? (a) 125° (b) 100° (c) 135° (d) 80°
  13. 13.Two straight lines cross. Two vertically opposite angles add up to 230°. What is each of the other two angles? (a) 115° (b) 65° (c) 130° (d) 66°
  14. 14.Two straight lines cross. One of the angles is 35°. What is the angle next to it on the same straight line? (a) 55° (b) 35° (c) 145° (d) 325°
  15. 15.Two angles of a triangle are 50° and 40°. What is the exterior angle at the third corner? (a) 130° (b) 140° (c) 270° (d) 90°
  16. 16.Two angles of a triangle are 65° and 80°. What is the exterior angle at the third corner? (a) 115° (b) 145° (c) 100° (d) 35°
  17. 17.Two angles of a triangle are 45° and 35°. What is the third angle? (a) 145° (b) 80° (c) 100° (d) 135°
  18. 18.Two straight lines cross. One of the angles is 70°. What is the angle next to it on the same straight line? (a) 290° (b) 110° (c) 20° (d) 70°
  19. 19.In an isosceles triangle, the angle between the two equal sides is 50°. What is each of the other two angles? (a) 65° (b) 50° (c) 40° (d) 130°
  20. 20.Two angles of a triangle are 20° and 70°. What is the exterior angle at the third corner? (a) 160° (b) 90° (c) 110° (d) 270°
  21. 21.Two angles of a triangle are 55° and 95°. What is the exterior angle at the third corner? (a) 125° (b) 150° (c) 30° (d) 85°
  22. 22.Two straight lines cross. One of the angles is 115°. What is the angle next to it on the same straight line? (a) 66° (b) 65° (c) 245° (d) 115°
  23. 23.Two angles of a triangle are 60° and 70°. What is the third angle? (a) 130° (b) 110° (c) 120° (d) 50°
  24. 24.In an isosceles triangle, the two equal angles are 40° each. What is the third angle? (a) 140° (b) 50° (c) 100° (d) 40°
  25. 25.Two straight lines cross. Two vertically opposite angles add up to 100°. What is each of the other two angles? (a) 80° (b) 50° (c) 260° (d) 130°
  26. 26.Two straight lines cross. Two vertically opposite angles add up to 340°. What is each of the other two angles? (a) 20° (b) 170° (c) 11° (d) 10°
  27. 27.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) 51° (c) 230° (d) 50°
  28. 28.Two straight lines cross. One of the angles is 145°. What is the angle next to it on the same straight line? (a) 36° (b) 145° (c) 215° (d) 35°
  29. 29.Two angles of a triangle are 60° and 50°. What is the third angle? (a) 110° (b) 130° (c) 70° (d) 120°
  30. 30.Two angles of a triangle are 35° and 135°. What is the third angle? (a) 170° (b) 10° (c) 145° (d) 45°
  31. 31.Two angles of a triangle are 65° and 65°. What is the third angle? (a) 50° (b) 230° (c) 115° (d) 130°
  32. 32.In an isosceles triangle, the angle between the two equal sides is 90°. What is each of the other two angles? (a) 46° (b) 90° (c) 45° (d) 55°
  33. 33.Two angles of a triangle are 60° and 80°. What is the exterior angle at the third corner? (a) 40° (b) 140° (c) 120° (d) 100°
  34. 34.Two angles of a triangle are 30° and 20°. What is the third angle? (a) 150° (b) 130° (c) 50° (d) 160°
  35. 35.Two straight lines cross. Two vertically opposite angles add up to 130°. What is each of the other two angles? (a) 115° (b) 65° (c) 230° (d) 50°
  36. 36.In an isosceles triangle, the two equal angles are 50° each. What is the third angle? (a) 130° (b) 40° (c) 80° (d) 50°
  37. 37.Two angles of a triangle are 70° and 50°. What is the third angle? (a) 120° (b) 60° (c) 130° (d) 110°
  38. 38.Two angles of a triangle are 80° and 65°. What is the third angle? (a) 145° (b) 100° (c) 115° (d) 35°
  39. 39.In an isosceles triangle, the two equal angles are 70° each. What is the third angle? (a) 70° (b) 20° (c) 110° (d) 40°
  40. 40.Two angles of a triangle are 70° and 35°. What is the exterior angle at the third corner? (a) 110° (b) 145° (c) 75° (d) 105°

Answer key

  1. 85°
  2. 70°
  3. 90°
  4. 95°
  5. 105°
  6. 95°
  7. 80°
  8. 130°
  9. 50°
  10. 10°
  11. 145°
  12. 100°
  13. 65°
  14. 145°
  15. 90°
  16. 145°
  17. 100°
  18. 110°
  19. 65°
  20. 90°
  21. 150°
  22. 65°
  23. 50°
  24. 100°
  25. 130°
  26. 10°
  27. 50°
  28. 35°
  29. 70°
  30. 10°
  31. 50°
  32. 45°
  33. 140°
  34. 130°
  35. 115°
  36. 80°
  37. 60°
  38. 35°
  39. 40°
  40. 105°

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