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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 455 · 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 longest side of a right-angled triangle is 13 cm and one of the other sides is 5 cm. How long is the third side (in cm)?
  2. 2.Can a triangle have sides of 9 cm, 7 cm and 15 cm? (a) Yes (b) No
  3. 3.In triangle ABC, angle A = 98° and angle B = 25°. What is angle C (in degrees)?
  4. 4.An exterior angle of a triangle is 79°. One of its two interior opposite angles is 56°. What is the other one (in degrees)?
  5. 5.The angles of a triangle are in the ratio 2 : 3 : 5. What is the smallest angle (in degrees)?
  6. 6.In triangle ABC, angle A = 74° and angle B = 64°. What is angle C (in degrees)?
  7. 7.In an isosceles triangle, the angle between the two equal sides is 112°. What is each of the other two angles (in degrees)?
  8. 8.In triangle ABC, angle A = 64° and angle B = 28°. What is angle C (in degrees)?
  9. 9.Can a triangle have sides of 6 cm, 15 cm and 9 cm? (a) Yes (b) No
  10. 10.In triangle ABC, angle A = 58° and angle B = 61°. What is angle C (in degrees)?
  11. 11.Can a triangle have sides of 10 cm, 26 cm and 12 cm? (a) Yes (b) No
  12. 12.In a right-angled triangle, one of the other two angles is 60°. What is the third angle (in degrees)?
  13. 13.The angles of a triangle are in the ratio 1 : 2 : 6. What is the smallest angle (in degrees)?
  14. 14.In triangle ABC, angle A = 95° and angle B = 49°. What is angle C (in degrees)?
  15. 15.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  16. 16.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  17. 17.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?
  18. 18.An exterior angle of a triangle is 103°. One of its two interior opposite angles is 36°. What is the other one (in degrees)?
  19. 19.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  20. 20.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  21. 21.In triangle ABC, angle A = 47° and angle B = 111°. What is angle C (in degrees)?
  22. 22.The two shorter sides of a right-angled triangle are 12 cm and 5 cm. How long is the longest side (in cm)?
  23. 23.Can a triangle have sides of 15 cm, 3 cm and 12 cm? (a) Yes (b) No
  24. 24.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)?
  25. 25.In an isosceles triangle, the angle between the two equal sides is 26°. What is each of the other two angles (in degrees)?
  26. 26.In a right-angled triangle, one of the other two angles is 22°. What is the third angle (in degrees)?
  27. 27.An exterior angle of a triangle is 45°. One of its two interior opposite angles is 23°. What is the other one (in degrees)?
  28. 28.The two interior opposite angles of a triangle are 30° and 59°. What is the exterior angle (in degrees)?
  29. 29.An exterior angle of a triangle is 93°. One of its two interior opposite angles is 47°. What is the other one (in degrees)?
  30. 30.Can a triangle have sides of 5 cm, 8 cm and 4 cm? (a) Yes (b) No
  31. 31.An exterior angle of a triangle is 111°. One of its two interior opposite angles is 56°. What is the other one (in degrees)?
  32. 32.The two interior opposite angles of a triangle are 64° and 74°. What is the exterior angle (in degrees)?
  33. 33.An exterior angle of a triangle is 141°. One of its two interior opposite angles is 62°. What is the other one (in degrees)?
  34. 34.In an isosceles triangle, the angle between the two equal sides is 104°. What is each of the other two angles (in degrees)?
  35. 35.In a right-angled triangle, one of the other two angles is 37°. What is the third angle (in degrees)?
  36. 36.In triangle ABC, angle A = 75° and angle B = 47°. What is angle C (in degrees)?
  37. 37.The two interior opposite angles of a triangle are 53° and 79°. What is the exterior angle (in degrees)?
  38. 38.In a right-angled triangle, one of the other two angles is 18°. What is the third angle (in degrees)?
  39. 39.In triangle ABC, angle A = 40° and angle B = 59°. What is angle C (in degrees)?
  40. 40.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)?

Answer key

  1. 12
  2. Yes
  3. 57
  4. 23
  5. 36
  6. 42
  7. 34
  8. 88
  9. No
  10. 61
  11. No
  12. 30
  13. 20
  14. 36
  15. 25
  16. 25
  17. 50
  18. 67
  19. 90
  20. 75
  21. 22
  22. 13
  23. No
  24. 8
  25. 77
  26. 68
  27. 22
  28. 89
  29. 46
  30. Yes
  31. 55
  32. 138
  33. 79
  34. 38
  35. 53
  36. 58
  37. 132
  38. 72
  39. 81
  40. 7

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