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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 237 · 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.In triangle ABC, angle A = 37° and angle B = 44°. What is angle C (in degrees)?
  2. 2.Can a triangle have sides of 10 cm, 12 cm and 24 cm? (a) No (b) Yes
  3. 3.In triangle ABC, angle A = 31° and angle B = 86°. What is angle C (in degrees)?
  4. 4.Can a triangle have sides of 7 cm, 8 cm and 8 cm? (a) No (b) Yes
  5. 5.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  6. 6.In a right-angled triangle, one of the other two angles is 62°. What is the third angle (in degrees)?
  7. 7.The angles of a triangle are in the ratio 2 : 3 : 5. What is the smallest angle (in degrees)?
  8. 8.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?
  9. 9.In triangle ABC, angle A = 56° and angle B = 44°. What is angle C (in degrees)?
  10. 10.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  11. 11.In a right-angled triangle, one of the other two angles is 76°. What is the third angle (in degrees)?
  12. 12.In a right-angled triangle, one of the other two angles is 21°. What is the third angle (in degrees)?
  13. 13.Can a triangle have sides of 5 cm, 12 cm and 22 cm? (a) Yes (b) No
  14. 14.In a right-angled triangle, one of the other two angles is 52°. What is the third angle (in degrees)?
  15. 15.The two interior opposite angles of a triangle are 22° and 70°. What is the exterior angle (in degrees)?
  16. 16.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  17. 17.Can a triangle have sides of 11 cm, 3 cm and 10 cm? (a) No (b) Yes
  18. 18.In triangle ABC, angle A = 27° and angle B = 29°. What is angle C (in degrees)?
  19. 19.In an isosceles triangle, the two equal angles are 82° each. What is the third angle (in degrees)?
  20. 20.In triangle ABC, angle A = 68° and angle B = 22°. What is angle C (in degrees)?
  21. 21.Can a triangle have sides of 6 cm, 4 cm and 6 cm? (a) Yes (b) No
  22. 22.In a right-angled triangle, one of the other two angles is 20°. What is the third angle (in degrees)?
  23. 23.Can a triangle have sides of 5 cm, 5 cm and 13 cm? (a) Yes (b) No
  24. 24.In triangle ABC, angle A = 43° and angle B = 86°. What is angle C (in degrees)?
  25. 25.In an isosceles triangle, the angle between the two equal sides is 44°. What is each of the other two angles (in degrees)?
  26. 26.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  27. 27.Can a triangle have sides of 21 cm, 9 cm and 10 cm? (a) Yes (b) No
  28. 28.In a right-angled triangle, one of the other two angles is 35°. What is the third angle (in degrees)?
  29. 29.In triangle ABC, angle A = 80° and angle B = 49°. What is angle C (in degrees)?
  30. 30.An exterior angle of a triangle is 73°. One of its two interior opposite angles is 30°. What is the other one (in degrees)?
  31. 31.The angles of a triangle are in the ratio 3 : 3 : 4. What is the smallest angle (in degrees)?
  32. 32.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  33. 33.In a right-angled triangle, one of the other two angles is 69°. What is the third angle (in degrees)?
  34. 34.The longest side of a right-angled triangle is 10 cm and one of the other sides is 8 cm. How long is the third side (in cm)?
  35. 35.In triangle ABC, angle A = 77° and angle B = 67°. What is angle C (in degrees)?
  36. 36.Can a triangle have sides of 2 cm, 2 cm and 9 cm? (a) Yes (b) No
  37. 37.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  38. 38.An exterior angle of a triangle is 122°. One of its two interior opposite angles is 64°. What is the other one (in degrees)?
  39. 39.In an isosceles triangle, the angle between the two equal sides is 66°. What is each of the other two angles (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 44°. What is the third angle (in degrees)?

Answer key

  1. 99
  2. No
  3. 63
  4. Yes
  5. 25
  6. 28
  7. 36
  8. 48
  9. 80
  10. 36
  11. 14
  12. 69
  13. No
  14. 38
  15. 92
  16. 90
  17. Yes
  18. 124
  19. 16
  20. 90
  21. Yes
  22. 70
  23. No
  24. 51
  25. 68
  26. 20
  27. No
  28. 55
  29. 51
  30. 43
  31. 54
  32. 100
  33. 21
  34. 6
  35. 36
  36. No
  37. 17
  38. 58
  39. 57
  40. 46

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