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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 616 · 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 65° and 34°. What is the exterior angle (in degrees)?
  2. 2.Can a triangle have sides of 11 cm, 6 cm and 13 cm? (a) Yes (b) No
  3. 3.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  4. 4.The two interior opposite angles of a triangle are 23° and 80°. What is the exterior angle (in degrees)?
  5. 5.Can a triangle have sides of 11 cm, 12 cm and 4 cm? (a) Yes (b) No
  6. 6.In an isosceles triangle, the angle between the two equal sides is 82°. What is each of the other two angles (in degrees)?
  7. 7.Can a triangle have sides of 10 cm, 10 cm and 2 cm? (a) No (b) Yes
  8. 8.In triangle ABC, angle A = 81° and angle B = 38°. What is angle C (in degrees)?
  9. 9.An exterior angle of a triangle is 123°. One of its two interior opposite angles is 77°. What is the other one (in degrees)?
  10. 10.Can a triangle have sides of 10 cm, 9 cm and 20 cm? (a) Yes (b) No
  11. 11.In a right-angled triangle, one of the other two angles is 66°. What is the third angle (in degrees)?
  12. 12.An exterior angle of a triangle is 146°. One of its two interior opposite angles is 74°. What is the other one (in degrees)?
  13. 13.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  14. 14.Can a triangle have sides of 9 cm, 10 cm and 12 cm? (a) No (b) Yes
  15. 15.In triangle ABC, angle A = 88° and angle B = 55°. What is angle C (in degrees)?
  16. 16.In a right-angled triangle, one of the other two angles is 39°. What is the third angle (in degrees)?
  17. 17.In an isosceles triangle, the angle between the two equal sides is 96°. What is each of the other two angles (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.The two shorter sides of a right-angled triangle are 24 cm and 18 cm. How long is the longest side (in cm)?
  20. 20.The two interior opposite angles of a triangle are 71° and 53°. What is the exterior angle (in degrees)?
  21. 21.In triangle ABC, angle A = 65° and angle B = 50°. What is angle C (in degrees)?
  22. 22.In a right-angled triangle, one of the other two angles is 28°. What is the third angle (in degrees)?
  23. 23.The longest side of a right-angled triangle is 39 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  24. 24.In a right-angled triangle, one of the other two angles is 75°. What is the third angle (in degrees)?
  25. 25.The two shorter sides of a right-angled triangle are 12 cm and 5 cm. How long is the longest side (in cm)?
  26. 26.In triangle ABC, angle A = 70° and angle B = 67°. What is angle C (in degrees)?
  27. 27.An exterior angle of a triangle is 109°. One of its two interior opposite angles is 71°. What is the other one (in degrees)?
  28. 28.Can a triangle have sides of 9 cm, 5 cm and 7 cm? (a) Yes (b) No
  29. 29.Can a triangle have sides of 12 cm, 10 cm and 11 cm? (a) No (b) Yes
  30. 30.In a right-angled triangle, one of the other two angles is 67°. What is the third angle (in degrees)?
  31. 31.In a right-angled triangle, one of the other two angles is 80°. What is the third angle (in degrees)?
  32. 32.The two interior opposite angles of a triangle are 22° and 68°. What is the exterior angle (in degrees)?
  33. 33.The two interior opposite angles of a triangle are 44° and 50°. What is the exterior angle (in degrees)?
  34. 34.In an isosceles triangle, the angle between the two equal sides is 84°. What is each of the other two angles (in degrees)?
  35. 35.In a right-angled triangle, one of the other two angles is 14°. What is the third angle (in degrees)?
  36. 36.In triangle ABC, angle A = 97° and angle B = 33°. What is angle C (in degrees)?
  37. 37.The two interior opposite angles of a triangle are 28° and 39°. What is the exterior angle (in degrees)?
  38. 38.The two interior opposite angles of a triangle are 31° and 65°. What is the exterior angle (in degrees)?
  39. 39.In triangle ABC, angle A = 44° and angle B = 71°. What is angle C (in degrees)?
  40. 40.In triangle ABC, angle A = 93° and angle B = 43°. What is angle C (in degrees)?

Answer key

  1. 99
  2. Yes
  3. 100
  4. 103
  5. Yes
  6. 49
  7. Yes
  8. 61
  9. 46
  10. No
  11. 24
  12. 72
  13. 45
  14. Yes
  15. 37
  16. 51
  17. 42
  18. 90
  19. 30
  20. 124
  21. 65
  22. 62
  23. 36
  24. 15
  25. 13
  26. 43
  27. 38
  28. Yes
  29. Yes
  30. 23
  31. 10
  32. 90
  33. 94
  34. 48
  35. 76
  36. 50
  37. 67
  38. 96
  39. 65
  40. 44

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