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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 185 · 40 sums
TalentJR

The method (Inside 180, outside the sum): Angle sum: ∠A + ∠B + ∠C = 180°. Exterior angle = sum of the two interior opposite angles. Right-angled triangle: longest side² = side² + side² (3, 4, 5 and 5, 12, 13 are famous sets). Sides can make a triangle only if the two shorter sides add up to more than the longest side.

NameDateTime takenScore ___ / 40
  1. 1.In an isosceles triangle, the angle between the two equal sides is 26°. What is each of the other two angles (in degrees)?
  2. 2.In a right-angled triangle, one of the other two angles is 34°. What is the third angle (in degrees)?
  3. 3.In a right-angled triangle, one of the other two angles is 79°. What is the third angle (in degrees)?
  4. 4.In triangle ABC, angle A = 23° and angle B = 31°. What is angle C (in degrees)?
  5. 5.Can a triangle have sides of 20 cm, 12 cm and 8 cm? (a) No (b) Yes
  6. 6.In an isosceles triangle, the angle between the two equal sides is 158°. What is each of the other two angles (in degrees)?
  7. 7.Can a triangle have sides of 12 cm, 23 cm and 10 cm? (a) Yes (b) No
  8. 8.The angles of a triangle are in the ratio 2 : 7 : 9. What is the biggest angle (in degrees)?
  9. 9.The angles of a triangle are in the ratio 3 : 5 : 7. What is the biggest angle (in degrees)?
  10. 10.In an isosceles triangle, the angle between the two equal sides is 122°. What is each of the other two angles (in degrees)?
  11. 11.In a right-angled triangle, one of the other two angles is 58°. What is the third angle (in degrees)?
  12. 12.In an isosceles triangle, the angle between the two equal sides is 124°. What is each of the other two angles (in degrees)?
  13. 13.The two interior opposite angles of a triangle are 76° and 37°. What is the exterior angle (in degrees)?
  14. 14.An exterior angle of a triangle is 95°. One of its two interior opposite angles is 58°. What is the other one (in degrees)?
  15. 15.In an isosceles triangle, the angle between the two equal sides is 22°. What is each of the other two angles (in degrees)?
  16. 16.In an isosceles triangle, the angle between the two equal sides is 154°. What is each of the other two angles (in degrees)?
  17. 17.Can a triangle have sides of 11 cm, 25 cm and 10 cm? (a) Yes (b) No
  18. 18.In triangle ABC, angle A = 38° and angle B = 114°. What is angle C (in degrees)?
  19. 19.Can a triangle have sides of 17 cm, 9 cm and 7 cm? (a) Yes (b) No
  20. 20.In triangle ABC, angle A = 58° and angle B = 96°. What is angle C (in degrees)?
  21. 21.The longest side of a right-angled triangle is 15 cm and one of the other sides is 12 cm. How long is the third side (in cm)?
  22. 22.Can a triangle have sides of 3 cm, 10 cm and 11 cm? (a) Yes (b) No
  23. 23.In triangle ABC, angle A = 93° and angle B = 66°. What is angle C (in degrees)?
  24. 24.Can a triangle have sides of 6 cm, 11 cm and 14 cm? (a) No (b) Yes
  25. 25.In a right-angled triangle, one of the other two angles is 72°. What is the third angle (in degrees)?
  26. 26.An exterior angle of a triangle is 122°. One of its two interior opposite angles is 63°. What is the other one (in degrees)?
  27. 27.An exterior angle of a triangle is 83°. One of its two interior opposite angles is 30°. What is the other one (in degrees)?
  28. 28.In triangle ABC, angle A = 20° and angle B = 63°. What is angle C (in degrees)?
  29. 29.In a right-angled triangle, one of the other two angles is 77°. What is the third angle (in degrees)?
  30. 30.Can a triangle have sides of 3 cm, 8 cm and 9 cm? (a) No (b) Yes
  31. 31.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  32. 32.In triangle ABC, angle A = 22° and angle B = 119°. What is angle C (in degrees)?
  33. 33.The two interior opposite angles of a triangle are 80° and 55°. What is the exterior angle (in degrees)?
  34. 34.In a right-angled triangle, one of the other two angles is 16°. What is the third angle (in degrees)?
  35. 35.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  36. 36.The two shorter sides of a right-angled triangle are 10 cm and 24 cm. How long is the longest side (in cm)?
  37. 37.In an isosceles triangle, the two equal angles are 39° each. What is the third angle (in degrees)?
  38. 38.In triangle ABC, angle A = 22° and angle B = 50°. What is angle C (in degrees)?
  39. 39.The angles of a triangle are in the ratio 1 : 2 : 6. What is the smallest angle (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 22°. What is the third angle (in degrees)?

Answer key

  1. 77
  2. 56
  3. 11
  4. 126
  5. No
  6. 11
  7. No
  8. 90
  9. 84
  10. 29
  11. 32
  12. 28
  13. 113
  14. 37
  15. 79
  16. 13
  17. No
  18. 28
  19. No
  20. 26
  21. 9
  22. Yes
  23. 21
  24. Yes
  25. 18
  26. 59
  27. 53
  28. 97
  29. 13
  30. Yes
  31. 36
  32. 39
  33. 135
  34. 74
  35. 17
  36. 26
  37. 102
  38. 108
  39. 20
  40. 68

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