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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 875 · 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 angles of a triangle are in the ratio 1 : 2 : 2. What is the biggest angle (in degrees)?
  2. 2.In an isosceles triangle, the two equal angles are 46° each. What is the third angle (in degrees)?
  3. 3.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  4. 4.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?
  5. 5.In triangle ABC, angle A = 36° and angle B = 42°. What is angle C (in degrees)?
  6. 6.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  7. 7.An exterior angle of a triangle is 65°. One of its two interior opposite angles is 24°. What is the other one (in degrees)?
  8. 8.The angles of a triangle are in the ratio 1 : 2 : 3. 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.Can a triangle have sides of 3 cm, 10 cm and 10 cm? (a) No (b) Yes
  11. 11.An exterior angle of a triangle is 55°. One of its two interior opposite angles is 34°. What is the other one (in degrees)?
  12. 12.In an isosceles triangle, the angle between the two equal sides is 90°. What is each of the other two angles (in degrees)?
  13. 13.In a right-angled triangle, one of the other two angles is 78°. What is the third angle (in degrees)?
  14. 14.The two interior opposite angles of a triangle are 31° and 43°. What is the exterior angle (in degrees)?
  15. 15.The two shorter sides of a right-angled triangle are 12 cm and 9 cm. How long is the longest side (in cm)?
  16. 16.An exterior angle of a triangle is 80°. One of its two interior opposite angles is 30°. What is the other one (in degrees)?
  17. 17.In triangle ABC, angle A = 64° and angle B = 43°. What is angle C (in degrees)?
  18. 18.In an isosceles triangle, the two equal angles are 50° each. What is the third angle (in degrees)?
  19. 19.In triangle ABC, angle A = 38° and angle B = 96°. What is angle C (in degrees)?
  20. 20.In a right-angled triangle, one of the other two angles is 80°. What is the third angle (in degrees)?
  21. 21.The angles of a triangle are in the ratio 1 : 2 : 6. What is the smallest angle (in degrees)?
  22. 22.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)?
  23. 23.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  24. 24.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  25. 25.In triangle ABC, angle A = 31° and angle B = 95°. What is angle C (in degrees)?
  26. 26.In a right-angled triangle, one of the other two angles is 25°. What is the third angle (in degrees)?
  27. 27.In triangle ABC, angle A = 86° and angle B = 40°. What is angle C (in degrees)?
  28. 28.Can a triangle have sides of 3 cm, 10 cm and 12 cm? (a) No (b) Yes
  29. 29.Can a triangle have sides of 7 cm, 9 cm and 19 cm? (a) Yes (b) No
  30. 30.In a right-angled triangle, one of the other two angles is 62°. What is the third angle (in degrees)?
  31. 31.The two shorter sides of a right-angled triangle are 18 cm and 24 cm. How long is the longest side (in cm)?
  32. 32.In triangle ABC, angle A = 36° and angle B = 35°. What is angle C (in degrees)?
  33. 33.The two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  34. 34.In an isosceles triangle, the angle between the two equal sides is 64°. What is each of the other two angles (in degrees)?
  35. 35.Can a triangle have sides of 9 cm, 3 cm and 11 cm? (a) No (b) Yes
  36. 36.In triangle ABC, angle A = 41° and angle B = 61°. What is angle C (in degrees)?
  37. 37.In an isosceles triangle, the angle between the two equal sides is 58°. What is each of the other two angles (in degrees)?
  38. 38.In triangle ABC, angle A = 49° and angle B = 71°. What is angle C (in degrees)?
  39. 39.In triangle ABC, angle A = 35° and angle B = 29°. What is angle C (in degrees)?
  40. 40.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?

Answer key

  1. 72
  2. 88
  3. 17
  4. 48
  5. 102
  6. 90
  7. 41
  8. 90
  9. 26
  10. Yes
  11. 21
  12. 45
  13. 12
  14. 74
  15. 15
  16. 50
  17. 73
  18. 80
  19. 46
  20. 10
  21. 20
  22. 15
  23. 80
  24. 25
  25. 54
  26. 65
  27. 54
  28. Yes
  29. No
  30. 28
  31. 30
  32. 109
  33. 39
  34. 58
  35. Yes
  36. 78
  37. 61
  38. 60
  39. 116
  40. 50

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