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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 891 · 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 97°. One of its two interior opposite angles is 24°. What is the other one (in degrees)?
  2. 2.In triangle ABC, angle A = 91° and angle B = 44°. What is angle C (in degrees)?
  3. 3.In triangle ABC, angle A = 36° and angle B = 103°. What is angle C (in degrees)?
  4. 4.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  5. 5.In triangle ABC, angle A = 67° and angle B = 81°. What is angle C (in degrees)?
  6. 6.In a right-angled triangle, one of the other two angles is 13°. What is the third angle (in degrees)?
  7. 7.An exterior angle of a triangle is 101°. One of its two interior opposite angles is 78°. What is the other one (in degrees)?
  8. 8.The longest side of a right-angled triangle is 25 cm and one of the other sides is 24 cm. How long is the third side (in cm)?
  9. 9.In a right-angled triangle, one of the other two angles is 66°. What is the third angle (in degrees)?
  10. 10.An exterior angle of a triangle is 64°. One of its two interior opposite angles is 38°. What is the other one (in degrees)?
  11. 11.In an isosceles triangle, the two equal angles are 43° each. What is the third angle (in degrees)?
  12. 12.In a right-angled triangle, one of the other two angles is 78°. What is the third angle (in degrees)?
  13. 13.In an isosceles triangle, the angle between the two equal sides is 102°. What is each of the other two angles (in degrees)?
  14. 14.Can a triangle have sides of 12 cm, 9 cm and 6 cm? (a) Yes (b) No
  15. 15.The angles of a triangle are in the ratio 2 : 7 : 9. What is the biggest angle (in degrees)?
  16. 16.Can a triangle have sides of 9 cm, 12 cm and 10 cm? (a) Yes (b) No
  17. 17.An exterior angle of a triangle is 104°. One of its two interior opposite angles is 59°. What is the other one (in degrees)?
  18. 18.In an isosceles triangle, the angle between the two equal sides is 124°. What is each of the other two angles (in degrees)?
  19. 19.In an isosceles triangle, the angle between the two equal sides is 154°. What is each of the other two angles (in degrees)?
  20. 20.In a right-angled triangle, one of the other two angles is 67°. What is the third angle (in degrees)?
  21. 21.The two interior opposite angles of a triangle are 58° and 62°. What is the exterior angle (in degrees)?
  22. 22.The two interior opposite angles of a triangle are 75° and 67°. What is the exterior angle (in degrees)?
  23. 23.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  24. 24.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  25. 25.In an isosceles triangle, the angle between the two equal sides is 116°. What is each of the other two angles (in degrees)?
  26. 26.In triangle ABC, angle A = 57° and angle B = 46°. What is angle C (in degrees)?
  27. 27.Can a triangle have sides of 8 cm, 9 cm and 2 cm? (a) Yes (b) No
  28. 28.In a right-angled triangle, one of the other two angles is 44°. What is the third angle (in degrees)?
  29. 29.Can a triangle have sides of 12 cm, 19 cm and 4 cm? (a) No (b) Yes
  30. 30.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)?
  31. 31.The longest side of a right-angled triangle is 26 cm and one of the other sides is 24 cm. How long is the third side (in cm)?
  32. 32.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)?
  33. 33.In triangle ABC, angle A = 52° and angle B = 28°. What is angle C (in degrees)?
  34. 34.In an isosceles triangle, the two equal angles are 50° each. What is the third angle (in degrees)?
  35. 35.Can a triangle have sides of 13 cm, 10 cm and 8 cm? (a) Yes (b) No
  36. 36.In a right-angled triangle, one of the other two angles is 15°. What is the third angle (in degrees)?
  37. 37.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)?
  38. 38.An exterior angle of a triangle is 75°. One of its two interior opposite angles is 52°. What is the other one (in degrees)?
  39. 39.In a right-angled triangle, one of the other two angles is 11°. What is the third angle (in degrees)?
  40. 40.The two shorter sides of a right-angled triangle are 36 cm and 15 cm. How long is the longest side (in cm)?

Answer key

  1. 73
  2. 45
  3. 41
  4. 100
  5. 32
  6. 77
  7. 23
  8. 7
  9. 24
  10. 26
  11. 94
  12. 12
  13. 39
  14. Yes
  15. 90
  16. Yes
  17. 45
  18. 28
  19. 13
  20. 23
  21. 120
  22. 142
  23. 17
  24. 25
  25. 32
  26. 77
  27. Yes
  28. 46
  29. No
  30. 15
  31. 10
  32. 36
  33. 100
  34. 80
  35. Yes
  36. 75
  37. 24
  38. 23
  39. 79
  40. 39

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