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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 506 · 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.An exterior angle of a triangle is 73°. One of its two interior opposite angles is 34°. What is the other one (in degrees)?
  2. 2.Can a triangle have sides of 7 cm, 2 cm and 6 cm? (a) No (b) Yes
  3. 3.An exterior angle of a triangle is 70°. One of its two interior opposite angles is 40°. What is the other one (in degrees)?
  4. 4.The two interior opposite angles of a triangle are 36° and 20°. What is the exterior angle (in degrees)?
  5. 5.In triangle ABC, angle A = 33° and angle B = 65°. What is angle C (in degrees)?
  6. 6.In a right-angled triangle, one of the other two angles is 73°. What is the third angle (in degrees)?
  7. 7.The longest side of a right-angled triangle is 17 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  8. 8.In triangle ABC, angle A = 24° and angle B = 124°. What is angle C (in degrees)?
  9. 9.In a right-angled triangle, one of the other two angles is 48°. What is the third angle (in degrees)?
  10. 10.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  11. 11.The two shorter sides of a right-angled triangle are 10 cm and 24 cm. How long is the longest side (in cm)?
  12. 12.Can a triangle have sides of 21 cm, 8 cm and 10 cm? (a) No (b) Yes
  13. 13.In an isosceles triangle, the two equal angles are 73° each. What is the third angle (in degrees)?
  14. 14.In an isosceles triangle, the angle between the two equal sides is 60°. What is each of the other two angles (in degrees)?
  15. 15.In a right-angled triangle, one of the other two angles is 18°. What is the third angle (in degrees)?
  16. 16.In a right-angled triangle, one of the other two angles is 52°. What is the third angle (in degrees)?
  17. 17.In a right-angled triangle, one of the other two angles is 23°. What is the third angle (in degrees)?
  18. 18.The longest side of a right-angled triangle is 25 cm and one of the other sides is 7 cm. How long is the third side (in cm)?
  19. 19.In triangle ABC, angle A = 93° and angle B = 62°. What is angle C (in degrees)?
  20. 20.In an isosceles triangle, the two equal angles are 50° each. What is the third angle (in degrees)?
  21. 21.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  22. 22.In triangle ABC, angle A = 82° and angle B = 20°. What is angle C (in degrees)?
  23. 23.In a right-angled triangle, one of the other two angles is 60°. What is the third angle (in degrees)?
  24. 24.In triangle ABC, angle A = 60° and angle B = 82°. What is angle C (in degrees)?
  25. 25.In triangle ABC, angle A = 90° and angle B = 44°. What is angle C (in degrees)?
  26. 26.In an isosceles triangle, the angle between the two equal sides is 110°. What is each of the other two angles (in degrees)?
  27. 27.In triangle ABC, angle A = 52° and angle B = 53°. What is angle C (in degrees)?
  28. 28.An exterior angle of a triangle is 92°. One of its two interior opposite angles is 27°. What is the other one (in degrees)?
  29. 29.Can a triangle have sides of 7 cm, 3 cm and 6 cm? (a) No (b) Yes
  30. 30.In a right-angled triangle, one of the other two angles is 57°. What is the third angle (in degrees)?
  31. 31.In triangle ABC, angle A = 72° and angle B = 87°. What is angle C (in degrees)?
  32. 32.Can a triangle have sides of 9 cm, 12 cm and 19 cm? (a) No (b) Yes
  33. 33.In triangle ABC, angle A = 41° and angle B = 33°. What is angle C (in degrees)?
  34. 34.In triangle ABC, angle A = 20° and angle B = 41°. What is angle C (in degrees)?
  35. 35.The longest side of a right-angled triangle is 39 cm and one of the other sides is 36 cm. How long is the third side (in cm)?
  36. 36.In triangle ABC, angle A = 86° and angle B = 28°. What is angle C (in degrees)?
  37. 37.In triangle ABC, angle A = 60° and angle B = 69°. What is angle C (in degrees)?
  38. 38.The two interior opposite angles of a triangle are 38° and 60°. What is the exterior angle (in degrees)?
  39. 39.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  40. 40.The two shorter sides of a right-angled triangle are 18 cm and 24 cm. How long is the longest side (in cm)?

Answer key

  1. 39
  2. Yes
  3. 30
  4. 56
  5. 82
  6. 17
  7. 8
  8. 32
  9. 42
  10. 40
  11. 26
  12. No
  13. 34
  14. 60
  15. 72
  16. 38
  17. 67
  18. 24
  19. 25
  20. 80
  21. 36
  22. 78
  23. 30
  24. 38
  25. 46
  26. 35
  27. 75
  28. 65
  29. Yes
  30. 33
  31. 21
  32. Yes
  33. 106
  34. 119
  35. 15
  36. 66
  37. 51
  38. 98
  39. 17
  40. 30

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