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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 850 · 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.The two interior opposite angles of a triangle are 59° and 28°. What is the exterior angle (in degrees)?
  2. 2.The two interior opposite angles of a triangle are 62° and 29°. What is the exterior angle (in degrees)?
  3. 3.An exterior angle of a triangle is 112°. One of its two interior opposite angles is 59°. What is the other one (in degrees)?
  4. 4.In triangle ABC, angle A = 61° and angle B = 37°. What is angle C (in degrees)?
  5. 5.In triangle ABC, angle A = 65° and angle B = 65°. What is angle C (in degrees)?
  6. 6.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  7. 7.In a right-angled triangle, one of the other two angles is 51°. What is the third angle (in degrees)?
  8. 8.The two shorter sides of a right-angled triangle are 5 cm and 12 cm. How long is the longest side (in cm)?
  9. 9.The two interior opposite angles of a triangle are 60° and 31°. What is the exterior angle (in degrees)?
  10. 10.In a right-angled triangle, one of the other two angles is 46°. What is the third angle (in degrees)?
  11. 11.In triangle ABC, angle A = 79° and angle B = 25°. What is angle C (in degrees)?
  12. 12.The angles of a triangle are in the ratio 3 : 5 : 7. What is the biggest angle (in degrees)?
  13. 13.In triangle ABC, angle A = 54° and angle B = 80°. What is angle C (in degrees)?
  14. 14.In an isosceles triangle, the two equal angles are 41° each. What is the third angle (in degrees)?
  15. 15.In an isosceles triangle, the two equal angles are 55° each. What is the third angle (in degrees)?
  16. 16.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?
  17. 17.In an isosceles triangle, the two equal angles are 35° each. What is the third angle (in degrees)?
  18. 18.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  19. 19.In an isosceles triangle, the two equal angles are 67° each. What is the third angle (in degrees)?
  20. 20.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  21. 21.In triangle ABC, angle A = 25° and angle B = 42°. What is angle C (in degrees)?
  22. 22.The two interior opposite angles of a triangle are 27° and 33°. What is the exterior angle (in degrees)?
  23. 23.The longest side of a right-angled triangle is 10 cm and one of the other sides is 6 cm. How long is the third side (in cm)?
  24. 24.An exterior angle of a triangle is 92°. One of its two interior opposite angles is 57°. What is the other one (in degrees)?
  25. 25.In triangle ABC, angle A = 93° and angle B = 30°. What is angle C (in degrees)?
  26. 26.In an isosceles triangle, the two equal angles are 51° each. What is the third angle (in degrees)?
  27. 27.Can a triangle have sides of 11 cm, 21 cm and 9 cm? (a) No (b) Yes
  28. 28.In a right-angled triangle, one of the other two angles is 18°. What is the third angle (in degrees)?
  29. 29.In a right-angled triangle, one of the other two angles is 63°. What is the third angle (in degrees)?
  30. 30.In a right-angled triangle, one of the other two angles is 44°. What is the third angle (in degrees)?
  31. 31.In triangle ABC, angle A = 37° and angle B = 57°. What is angle C (in degrees)?
  32. 32.In triangle ABC, angle A = 99° and angle B = 31°. What is angle C (in degrees)?
  33. 33.In a right-angled triangle, one of the other two angles is 37°. What is the third angle (in degrees)?
  34. 34.The two interior opposite angles of a triangle are 73° and 77°. What is the exterior angle (in degrees)?
  35. 35.Can a triangle have sides of 3 cm, 9 cm and 7 cm? (a) No (b) Yes
  36. 36.In triangle ABC, angle A = 40° and angle B = 63°. What is angle C (in degrees)?
  37. 37.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?
  38. 38.The angles of a triangle are in the ratio 1 : 2 : 6. What is the smallest angle (in degrees)?
  39. 39.Can a triangle have sides of 10 cm, 7 cm and 10 cm? (a) No (b) Yes
  40. 40.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)?

Answer key

  1. 87
  2. 91
  3. 53
  4. 82
  5. 50
  6. 36
  7. 39
  8. 13
  9. 91
  10. 44
  11. 76
  12. 84
  13. 46
  14. 98
  15. 70
  16. 48
  17. 110
  18. 90
  19. 46
  20. 40
  21. 113
  22. 60
  23. 8
  24. 35
  25. 57
  26. 78
  27. No
  28. 72
  29. 27
  30. 46
  31. 86
  32. 50
  33. 53
  34. 150
  35. Yes
  36. 77
  37. 50
  38. 20
  39. Yes
  40. 15

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