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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 114 · 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.Can a triangle have sides of 7 cm, 15 cm and 8 cm? (a) Yes (b) No
  2. 2.The two interior opposite angles of a triangle are 29° and 58°. What is the exterior angle (in degrees)?
  3. 3.Can a triangle have sides of 10 cm, 2 cm and 3 cm? (a) Yes (b) No
  4. 4.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  5. 5.An exterior angle of a triangle is 86°. One of its two interior opposite angles is 62°. What is the other one (in degrees)?
  6. 6.In an isosceles triangle, the angle between the two equal sides is 74°. What is each of the other two angles (in degrees)?
  7. 7.The angles of a triangle are in the ratio 3 : 5 : 7. What is the biggest angle (in degrees)?
  8. 8.Can a triangle have sides of 4 cm, 4 cm and 12 cm? (a) No (b) Yes
  9. 9.In an isosceles triangle, the two equal angles are 79° each. What is the third angle (in degrees)?
  10. 10.In a right-angled triangle, one of the other two angles is 66°. What is the third angle (in degrees)?
  11. 11.In triangle ABC, angle A = 98° and angle B = 60°. What is angle C (in degrees)?
  12. 12.In an isosceles triangle, the two equal angles are 62° each. What is the third angle (in degrees)?
  13. 13.In a right-angled triangle, one of the other two angles is 22°. What is the third angle (in degrees)?
  14. 14.In an isosceles triangle, the two equal angles are 60° each. What is the third angle (in degrees)?
  15. 15.In triangle ABC, angle A = 81° and angle B = 59°. What is angle C (in degrees)?
  16. 16.In a right-angled triangle, one of the other two angles is 77°. What is the third angle (in degrees)?
  17. 17.The angles of a triangle are in the ratio 5 : 6 : 7. What is the biggest angle (in degrees)?
  18. 18.In an isosceles triangle, the angle between the two equal sides is 94°. What is each of the other two angles (in degrees)?
  19. 19.In a right-angled triangle, one of the other two angles is 12°. What is the third angle (in degrees)?
  20. 20.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)?
  21. 21.Can a triangle have sides of 20 cm, 11 cm and 5 cm? (a) Yes (b) No
  22. 22.Can a triangle have sides of 11 cm, 17 cm and 6 cm? (a) Yes (b) No
  23. 23.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  24. 24.Can a triangle have sides of 10 cm, 11 cm and 11 cm? (a) No (b) Yes
  25. 25.The two shorter sides of a right-angled triangle are 36 cm and 15 cm. How long is the longest side (in cm)?
  26. 26.In triangle ABC, angle A = 23° and angle B = 97°. What is angle C (in degrees)?
  27. 27.The two shorter sides of a right-angled triangle are 24 cm and 18 cm. How long is the longest side (in cm)?
  28. 28.In triangle ABC, angle A = 99° and angle B = 37°. What is angle C (in degrees)?
  29. 29.In triangle ABC, angle A = 67° and angle B = 47°. What is angle C (in degrees)?
  30. 30.The two interior opposite angles of a triangle are 24° and 73°. What is the exterior angle (in degrees)?
  31. 31.In an isosceles triangle, the angle between the two equal sides is 100°. What is each of the other two angles (in degrees)?
  32. 32.In triangle ABC, angle A = 33° and angle B = 114°. What is angle C (in degrees)?
  33. 33.In triangle ABC, angle A = 20° and angle B = 121°. What is angle C (in degrees)?
  34. 34.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  35. 35.Can a triangle have sides of 22 cm, 7 cm and 10 cm? (a) No (b) Yes
  36. 36.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  37. 37.The two interior opposite angles of a triangle are 37° and 73°. What is the exterior angle (in degrees)?
  38. 38.In triangle ABC, angle A = 92° and angle B = 24°. What is angle C (in degrees)?
  39. 39.The two interior opposite angles of a triangle are 54° and 49°. What is the exterior angle (in degrees)?
  40. 40.Can a triangle have sides of 9 cm, 23 cm and 12 cm? (a) Yes (b) No

Answer key

  1. No
  2. 87
  3. No
  4. 80
  5. 24
  6. 53
  7. 84
  8. No
  9. 22
  10. 24
  11. 22
  12. 56
  13. 68
  14. 60
  15. 40
  16. 13
  17. 70
  18. 43
  19. 78
  20. 8
  21. No
  22. No
  23. 100
  24. Yes
  25. 39
  26. 60
  27. 30
  28. 44
  29. 66
  30. 97
  31. 40
  32. 33
  33. 39
  34. 25
  35. No
  36. 25
  37. 110
  38. 64
  39. 103
  40. No

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