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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 782 · 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 shorter sides of a right-angled triangle are 8 cm and 6 cm. How long is the longest side (in cm)?
  2. 2.The angles of a triangle are in the ratio 5 : 6 : 7. What is the biggest angle (in degrees)?
  3. 3.In an isosceles triangle, the angle between the two equal sides is 74°. What is each of the other two angles (in degrees)?
  4. 4.In triangle ABC, angle A = 75° and angle B = 59°. What is angle C (in degrees)?
  5. 5.In triangle ABC, angle A = 49° and angle B = 26°. What is angle C (in degrees)?
  6. 6.In an isosceles triangle, the angle between the two equal sides is 154°. What is each of the other two angles (in degrees)?
  7. 7.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  8. 8.In triangle ABC, angle A = 95° and angle B = 53°. What is angle C (in degrees)?
  9. 9.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  10. 10.In a right-angled triangle, one of the other two angles is 78°. What is the third angle (in degrees)?
  11. 11.The two interior opposite angles of a triangle are 77° and 24°. What is the exterior angle (in degrees)?
  12. 12.An exterior angle of a triangle is 71°. One of its two interior opposite angles is 42°. What is the other one (in degrees)?
  13. 13.In triangle ABC, angle A = 28° and angle B = 111°. What is angle C (in degrees)?
  14. 14.In triangle ABC, angle A = 40° and angle B = 82°. What is angle C (in degrees)?
  15. 15.In an isosceles triangle, the angle between the two equal sides is 58°. What is each of the other two angles (in degrees)?
  16. 16.In triangle ABC, angle A = 59° and angle B = 76°. What is angle C (in degrees)?
  17. 17.Can a triangle have sides of 4 cm, 4 cm and 4 cm? (a) No (b) Yes
  18. 18.In triangle ABC, angle A = 49° and angle B = 74°. What is angle C (in degrees)?
  19. 19.In triangle ABC, angle A = 40° and angle B = 21°. What is angle C (in degrees)?
  20. 20.Can a triangle have sides of 12 cm, 9 cm and 24 cm? (a) No (b) Yes
  21. 21.In a right-angled triangle, one of the other two angles is 75°. What is the third angle (in degrees)?
  22. 22.An exterior angle of a triangle is 119°. One of its two interior opposite angles is 61°. What is the other one (in degrees)?
  23. 23.In an isosceles triangle, the two equal angles are 60° each. What is the third angle (in degrees)?
  24. 24.An exterior angle of a triangle is 64°. One of its two interior opposite angles is 23°. What is the other one (in degrees)?
  25. 25.In triangle ABC, angle A = 43° and angle B = 20°. What is angle C (in degrees)?
  26. 26.Can a triangle have sides of 9 cm, 4 cm and 15 cm? (a) Yes (b) No
  27. 27.In a right-angled triangle, one of the other two angles is 16°. What is the third angle (in degrees)?
  28. 28.Can a triangle have sides of 12 cm, 7 cm and 24 cm? (a) Yes (b) No
  29. 29.In a right-angled triangle, one of the other two angles is 47°. What is the third angle (in degrees)?
  30. 30.The two interior opposite angles of a triangle are 68° and 58°. What is the exterior angle (in degrees)?
  31. 31.The longest side of a right-angled triangle is 30 cm and one of the other sides is 18 cm. How long is the third side (in cm)?
  32. 32.In an isosceles triangle, the angle between the two equal sides is 118°. What is each of the other two angles (in degrees)?
  33. 33.Can a triangle have sides of 10 cm, 11 cm and 4 cm? (a) No (b) Yes
  34. 34.In an isosceles triangle, the two equal angles are 72° each. What is the third angle (in degrees)?
  35. 35.An exterior angle of a triangle is 95°. One of its two interior opposite angles is 71°. What is the other one (in degrees)?
  36. 36.An exterior angle of a triangle is 81°. One of its two interior opposite angles is 54°. What is the other one (in degrees)?
  37. 37.Can a triangle have sides of 4 cm, 5 cm and 4 cm? (a) No (b) Yes
  38. 38.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  39. 39.In an isosceles triangle, the two equal angles are 25° each. What is the third angle (in degrees)?
  40. 40.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?

Answer key

  1. 10
  2. 70
  3. 53
  4. 46
  5. 105
  6. 13
  7. 45
  8. 32
  9. 90
  10. 12
  11. 101
  12. 29
  13. 41
  14. 58
  15. 61
  16. 45
  17. Yes
  18. 57
  19. 119
  20. No
  21. 15
  22. 58
  23. 60
  24. 41
  25. 117
  26. No
  27. 74
  28. No
  29. 43
  30. 126
  31. 24
  32. 31
  33. Yes
  34. 36
  35. 24
  36. 27
  37. Yes
  38. 25
  39. 130
  40. 100

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