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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 247 · 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 = 55° and angle B = 29°. What is angle C (in degrees)?
  2. 2.Can a triangle have sides of 8 cm, 3 cm and 11 cm? (a) Yes (b) No
  3. 3.The longest side of a right-angled triangle is 15 cm and one of the other sides is 9 cm. How long is the third side (in cm)?
  4. 4.In an isosceles triangle, the two equal angles are 53° each. What is the third angle (in degrees)?
  5. 5.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?
  6. 6.In a right-angled triangle, one of the other two angles is 12°. What is the third angle (in degrees)?
  7. 7.The two interior opposite angles of a triangle are 44° and 60°. What is the exterior angle (in degrees)?
  8. 8.In triangle ABC, angle A = 50° and angle B = 62°. What is angle C (in degrees)?
  9. 9.In a right-angled triangle, one of the other two angles is 10°. What is the third angle (in degrees)?
  10. 10.In a right-angled triangle, one of the other two angles is 28°. What is the third angle (in degrees)?
  11. 11.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  12. 12.An exterior angle of a triangle is 99°. One of its two interior opposite angles is 30°. What is the other one (in degrees)?
  13. 13.Can a triangle have sides of 21 cm, 12 cm and 4 cm? (a) No (b) Yes
  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 = 68° and angle B = 53°. What is angle C (in degrees)?
  16. 16.In triangle ABC, angle A = 73° and angle B = 67°. What is angle C (in degrees)?
  17. 17.In a right-angled triangle, one of the other two angles is 14°. What is the third angle (in degrees)?
  18. 18.In triangle ABC, angle A = 43° and angle B = 64°. What is angle C (in degrees)?
  19. 19.The angles of a triangle are in the ratio 1 : 2 : 2. What is the smallest angle (in degrees)?
  20. 20.Can a triangle have sides of 10 cm, 11 cm and 21 cm? (a) No (b) Yes
  21. 21.In an isosceles triangle, the angle between the two equal sides is 78°. What is each of the other two angles (in degrees)?
  22. 22.In a right-angled triangle, one of the other two angles is 73°. What is the third angle (in degrees)?
  23. 23.An exterior angle of a triangle is 110°. One of its two interior opposite angles is 48°. What is the other one (in degrees)?
  24. 24.In an isosceles triangle, the two equal angles are 61° each. What is the third angle (in degrees)?
  25. 25.In triangle ABC, angle A = 81° and angle B = 23°. What is angle C (in degrees)?
  26. 26.An exterior angle of a triangle is 120°. One of its two interior opposite angles is 74°. What is the other one (in degrees)?
  27. 27.In triangle ABC, angle A = 59° and angle B = 38°. What is angle C (in degrees)?
  28. 28.An exterior angle of a triangle is 122°. One of its two interior opposite angles is 70°. What is the other one (in degrees)?
  29. 29.In a right-angled triangle, one of the other two angles is 11°. What is the third angle (in degrees)?
  30. 30.In an isosceles triangle, the angle between the two equal sides is 62°. What is each of the other two angles (in degrees)?
  31. 31.In triangle ABC, angle A = 46° and angle B = 83°. What is angle C (in degrees)?
  32. 32.The longest side of a right-angled triangle is 15 cm and one of the other sides is 12 cm. How long is the third side (in cm)?
  33. 33.In a right-angled triangle, one of the other two angles is 13°. What is the third angle (in degrees)?
  34. 34.In a right-angled triangle, one of the other two angles is 64°. What is the third angle (in degrees)?
  35. 35.The two interior opposite angles of a triangle are 31° and 78°. What is the exterior angle (in degrees)?
  36. 36.Can a triangle have sides of 10 cm, 7 cm and 5 cm? (a) Yes (b) No
  37. 37.In an isosceles triangle, the two equal angles are 41° each. What is the third angle (in degrees)?
  38. 38.In a right-angled triangle, one of the other two angles is 72°. What is the third angle (in degrees)?
  39. 39.In triangle ABC, angle A = 25° and angle B = 73°. What is angle C (in degrees)?
  40. 40.The angles of a triangle are in the ratio 2 : 7 : 9. What is the biggest angle (in degrees)?

Answer key

  1. 96
  2. No
  3. 12
  4. 74
  5. 48
  6. 78
  7. 104
  8. 68
  9. 80
  10. 62
  11. 90
  12. 69
  13. No
  14. 60
  15. 59
  16. 40
  17. 76
  18. 73
  19. 36
  20. No
  21. 51
  22. 17
  23. 62
  24. 58
  25. 76
  26. 46
  27. 83
  28. 52
  29. 79
  30. 59
  31. 51
  32. 9
  33. 77
  34. 26
  35. 109
  36. Yes
  37. 98
  38. 18
  39. 82
  40. 90

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