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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 92 · 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.Can a triangle have sides of 4 cm, 3 cm and 6 cm? (a) No (b) Yes
  2. 2.In an isosceles triangle, the angle between the two equal sides is 84°. What is each of the other two angles (in degrees)?
  3. 3.Can a triangle have sides of 8 cm, 2 cm and 7 cm? (a) No (b) Yes
  4. 4.The two shorter sides of a right-angled triangle are 16 cm and 12 cm. How long is the longest side (in cm)?
  5. 5.In triangle ABC, angle A = 91° and angle B = 25°. What is angle C (in degrees)?
  6. 6.Can a triangle have sides of 11 cm, 5 cm and 12 cm? (a) Yes (b) No
  7. 7.In triangle ABC, angle A = 91° and angle B = 31°. What is angle C (in degrees)?
  8. 8.The angles of a triangle are in the ratio 1 : 2 : 2. What is the biggest angle (in degrees)?
  9. 9.The two shorter sides of a right-angled triangle are 10 cm and 24 cm. How long is the longest side (in cm)?
  10. 10.An exterior angle of a triangle is 91°. One of its two interior opposite angles is 44°. What is the other one (in degrees)?
  11. 11.An exterior angle of a triangle is 43°. One of its two interior opposite angles is 22°. What is the other one (in degrees)?
  12. 12.The angles of a triangle are in the ratio 2 : 2 : 5. What is the smallest angle (in degrees)?
  13. 13.An exterior angle of a triangle is 81°. One of its two interior opposite angles is 41°. What is the other one (in degrees)?
  14. 14.The longest side of a right-angled triangle is 25 cm and one of the other sides is 20 cm. How long is the third side (in cm)?
  15. 15.In an isosceles triangle, the angle between the two equal sides is 52°. What is each of the other two angles (in degrees)?
  16. 16.In triangle ABC, angle A = 40° and angle B = 35°. What is angle C (in degrees)?
  17. 17.The two interior opposite angles of a triangle are 53° and 30°. What is the exterior angle (in degrees)?
  18. 18.An exterior angle of a triangle is 116°. One of its two interior opposite angles is 75°. What is the other one (in degrees)?
  19. 19.An exterior angle of a triangle is 102°. One of its two interior opposite angles is 79°. What is the other one (in degrees)?
  20. 20.In an isosceles triangle, the two equal angles are 48° each. What is the third angle (in degrees)?
  21. 21.Can a triangle have sides of 12 cm, 13 cm and 7 cm? (a) No (b) Yes
  22. 22.In triangle ABC, angle A = 90° and angle B = 39°. What is angle C (in degrees)?
  23. 23.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  24. 24.The two interior opposite angles of a triangle are 44° and 25°. What is the exterior angle (in degrees)?
  25. 25.In an isosceles triangle, the angle between the two equal sides is 22°. What is each of the other two angles (in degrees)?
  26. 26.In a right-angled triangle, one of the other two angles is 10°. What is the third angle (in degrees)?
  27. 27.Can a triangle have sides of 7 cm, 8 cm and 14 cm? (a) Yes (b) No
  28. 28.Can a triangle have sides of 6 cm, 3 cm and 8 cm? (a) Yes (b) No
  29. 29.In a right-angled triangle, one of the other two angles is 53°. What is the third angle (in degrees)?
  30. 30.In triangle ABC, angle A = 45° and angle B = 42°. What is angle C (in degrees)?
  31. 31.Can a triangle have sides of 5 cm, 10 cm and 6 cm? (a) Yes (b) No
  32. 32.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)?
  33. 33.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  34. 34.Can a triangle have sides of 2 cm, 4 cm and 5 cm? (a) Yes (b) No
  35. 35.In a right-angled triangle, one of the other two angles is 16°. What is the third angle (in degrees)?
  36. 36.In an isosceles triangle, the two equal angles are 64° each. What is the third angle (in degrees)?
  37. 37.The two interior opposite angles of a triangle are 77° and 38°. What is the exterior angle (in degrees)?
  38. 38.In a right-angled triangle, one of the other two angles is 44°. What is the third angle (in degrees)?
  39. 39.In a right-angled triangle, one of the other two angles is 13°. What is the third angle (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 73°. What is the third angle (in degrees)?

Answer key

  1. Yes
  2. 48
  3. Yes
  4. 20
  5. 64
  6. Yes
  7. 58
  8. 72
  9. 26
  10. 47
  11. 21
  12. 40
  13. 40
  14. 15
  15. 64
  16. 105
  17. 83
  18. 41
  19. 23
  20. 84
  21. Yes
  22. 51
  23. 72
  24. 69
  25. 79
  26. 80
  27. Yes
  28. Yes
  29. 37
  30. 93
  31. Yes
  32. 24
  33. 75
  34. Yes
  35. 74
  36. 52
  37. 115
  38. 46
  39. 77
  40. 17

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