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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 730 · 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.

NameDateTime takenScore ___ / 40
  1. 1.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  2. 2.Can a triangle have sides of 11 cm, 9 cm and 4 cm? (a) Yes (b) No
  3. 3.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  4. 4.In an isosceles triangle, the two equal angles are 36° each. What is the third angle (in degrees)?
  5. 5.In a right-angled triangle, one of the other two angles is 10°. What is the third angle (in degrees)?
  6. 6.In a right-angled triangle, one of the other two angles is 45°. What is the third angle (in degrees)?
  7. 7.In an isosceles triangle, the angle between the two equal sides is 56°. What is each of the other two angles (in degrees)?
  8. 8.In triangle ABC, angle A = 34° and angle B = 104°. What is angle C (in degrees)?
  9. 9.In a right-angled triangle, one of the other two angles is 11°. What is the third angle (in degrees)?
  10. 10.In a right-angled triangle, one of the other two angles is 58°. What is the third angle (in degrees)?
  11. 11.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)?
  12. 12.In a right-angled triangle, one of the other two angles is 33°. What is the third angle (in degrees)?
  13. 13.Can a triangle have sides of 13 cm, 2 cm and 12 cm? (a) No (b) Yes
  14. 14.In triangle ABC, angle A = 52° and angle B = 62°. What is angle C (in degrees)?
  15. 15.In an isosceles triangle, the angle between the two equal sides is 152°. What is each of the other two angles (in degrees)?
  16. 16.In triangle ABC, angle A = 91° and angle B = 54°. What is angle C (in degrees)?
  17. 17.In an isosceles triangle, the two equal angles are 55° each. What is the third angle (in degrees)?
  18. 18.Can a triangle have sides of 6 cm, 4 cm and 11 cm? (a) No (b) Yes
  19. 19.The two interior opposite angles of a triangle are 31° and 72°. What is the exterior angle (in degrees)?
  20. 20.Can a triangle have sides of 7 cm, 5 cm and 3 cm? (a) No (b) Yes
  21. 21.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)?
  22. 22.An exterior angle of a triangle is 98°. One of its two interior opposite angles is 25°. What is the other one (in degrees)?
  23. 23.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  24. 24.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)?
  25. 25.In triangle ABC, angle A = 68° and angle B = 39°. What is angle C (in degrees)?
  26. 26.In an isosceles triangle, the two equal angles are 75° each. What is the third angle (in degrees)?
  27. 27.The two shorter sides of a right-angled triangle are 5 cm and 12 cm. How long is the longest side (in cm)?
  28. 28.In an isosceles triangle, the angle between the two equal sides is 142°. What is each of the other two angles (in degrees)?
  29. 29.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  30. 30.In a right-angled triangle, one of the other two angles is 60°. What is the third angle (in degrees)?
  31. 31.In a right-angled triangle, one of the other two angles is 57°. What is the third angle (in degrees)?
  32. 32.In an isosceles triangle, the angle between the two equal sides is 38°. What is each of the other two angles (in degrees)?
  33. 33.Can a triangle have sides of 17 cm, 3 cm and 11 cm? (a) Yes (b) No
  34. 34.The two interior opposite angles of a triangle are 64° and 65°. What is the exterior angle (in degrees)?
  35. 35.In a right-angled triangle, one of the other two angles is 74°. What is the third angle (in degrees)?
  36. 36.Can a triangle have sides of 16 cm, 7 cm and 7 cm? (a) Yes (b) No
  37. 37.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  38. 38.In triangle ABC, angle A = 57° and angle B = 86°. What is angle C (in degrees)?
  39. 39.The two interior opposite angles of a triangle are 76° and 69°. What is the exterior angle (in degrees)?
  40. 40.Can a triangle have sides of 9 cm, 5 cm and 19 cm? (a) Yes (b) No

Answer key

  1. 20
  2. Yes
  3. 25
  4. 108
  5. 80
  6. 45
  7. 62
  8. 42
  9. 79
  10. 32
  11. 12
  12. 57
  13. Yes
  14. 66
  15. 14
  16. 35
  17. 70
  18. No
  19. 103
  20. Yes
  21. 24
  22. 73
  23. 36
  24. 7
  25. 73
  26. 30
  27. 13
  28. 19
  29. 90
  30. 30
  31. 33
  32. 71
  33. No
  34. 129
  35. 16
  36. No
  37. 20
  38. 37
  39. 145
  40. No

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