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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 742 · 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.

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  1. 1.An exterior angle of a triangle is 106°. One of its two interior opposite angles is 33°. What is the other one (in degrees)?
  2. 2.In triangle ABC, angle A = 69° and angle B = 52°. What is angle C (in degrees)?
  3. 3.In an isosceles triangle, the two equal angles are 66° each. What is the third angle (in degrees)?
  4. 4.In a right-angled triangle, one of the other two angles is 60°. What is the third angle (in degrees)?
  5. 5.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  6. 6.In an isosceles triangle, the angle between the two equal sides is 126°. What is each of the other two angles (in degrees)?
  7. 7.An exterior angle of a triangle is 96°. One of its two interior opposite angles is 71°. What is the other one (in degrees)?
  8. 8.Can a triangle have sides of 3 cm, 2 cm and 5 cm? (a) No (b) Yes
  9. 9.An exterior angle of a triangle is 131°. One of its two interior opposite angles is 80°. What is the other one (in degrees)?
  10. 10.In triangle ABC, angle A = 93° and angle B = 51°. What is angle C (in degrees)?
  11. 11.Can a triangle have sides of 21 cm, 9 cm and 7 cm? (a) No (b) Yes
  12. 12.The two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  13. 13.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  14. 14.The two interior opposite angles of a triangle are 29° and 24°. What is the exterior angle (in degrees)?
  15. 15.In triangle ABC, angle A = 66° and angle B = 27°. What is angle C (in degrees)?
  16. 16.In a right-angled triangle, one of the other two angles is 18°. What is the third angle (in degrees)?
  17. 17.The longest side of a right-angled triangle is 17 cm and one of the other sides is 8 cm. How long is the third side (in cm)?
  18. 18.In a right-angled triangle, one of the other two angles is 54°. What is the third angle (in degrees)?
  19. 19.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  20. 20.In a right-angled triangle, one of the other two angles is 46°. What is the third angle (in degrees)?
  21. 21.In triangle ABC, angle A = 43° and angle B = 113°. What is angle C (in degrees)?
  22. 22.In an isosceles triangle, the two equal angles are 80° each. What is the third angle (in degrees)?
  23. 23.Can a triangle have sides of 10 cm, 12 cm and 11 cm? (a) Yes (b) No
  24. 24.In a right-angled triangle, one of the other two angles is 31°. What is the third angle (in degrees)?
  25. 25.In a right-angled triangle, one of the other two angles is 62°. What is the third angle (in degrees)?
  26. 26.In a right-angled triangle, one of the other two angles is 20°. What is the third angle (in degrees)?
  27. 27.In triangle ABC, angle A = 89° and angle B = 26°. What is angle C (in degrees)?
  28. 28.In a right-angled triangle, one of the other two angles is 50°. What is the third angle (in degrees)?
  29. 29.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  30. 30.The two interior opposite angles of a triangle are 43° and 37°. What is the exterior angle (in degrees)?
  31. 31.In triangle ABC, angle A = 90° and angle B = 61°. What is angle C (in degrees)?
  32. 32.In triangle ABC, angle A = 76° and angle B = 39°. What is angle C (in degrees)?
  33. 33.In a right-angled triangle, one of the other two angles is 27°. What is the third angle (in degrees)?
  34. 34.In triangle ABC, angle A = 20° and angle B = 55°. What is angle C (in degrees)?
  35. 35.The two shorter sides of a right-angled triangle are 24 cm and 10 cm. How long is the longest side (in cm)?
  36. 36.The two interior opposite angles of a triangle are 51° and 33°. What is the exterior angle (in degrees)?
  37. 37.In triangle ABC, angle A = 81° and angle B = 37°. What is angle C (in degrees)?
  38. 38.The two interior opposite angles of a triangle are 67° and 56°. What is the exterior angle (in degrees)?
  39. 39.In triangle ABC, angle A = 38° and angle B = 106°. What is angle C (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 76°. What is the third angle (in degrees)?

Answer key

  1. 73
  2. 59
  3. 48
  4. 30
  5. 90
  6. 27
  7. 25
  8. No
  9. 51
  10. 36
  11. No
  12. 39
  13. 90
  14. 53
  15. 87
  16. 72
  17. 15
  18. 36
  19. 40
  20. 44
  21. 24
  22. 20
  23. Yes
  24. 59
  25. 28
  26. 70
  27. 65
  28. 40
  29. 100
  30. 80
  31. 29
  32. 65
  33. 63
  34. 105
  35. 26
  36. 84
  37. 62
  38. 123
  39. 36
  40. 14

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