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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 359 · 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 5 : 6 : 7. What is the smallest angle (in degrees)?
  2. 2.Can a triangle have sides of 3 cm, 15 cm and 12 cm? (a) Yes (b) No
  3. 3.An exterior angle of a triangle is 143°. One of its two interior opposite angles is 76°. What is the other one (in degrees)?
  4. 4.In triangle ABC, angle A = 64° and angle B = 35°. What is angle C (in degrees)?
  5. 5.The longest side of a right-angled triangle is 26 cm and one of the other sides is 24 cm. How long is the third side (in cm)?
  6. 6.In triangle ABC, angle A = 89° and angle B = 42°. What is angle C (in degrees)?
  7. 7.Can a triangle have sides of 23 cm, 12 cm and 9 cm? (a) Yes (b) No
  8. 8.The longest side of a right-angled triangle is 17 cm and one of the other sides is 8 cm. How long is the third side (in cm)?
  9. 9.In an isosceles triangle, the angle between the two equal sides is 148°. What is each of the other two angles (in degrees)?
  10. 10.Can a triangle have sides of 10 cm, 22 cm and 10 cm? (a) No (b) Yes
  11. 11.In an isosceles triangle, the angle between the two equal sides is 34°. What is each of the other two angles (in degrees)?
  12. 12.An exterior angle of a triangle is 87°. One of its two interior opposite angles is 31°. What is the other one (in degrees)?
  13. 13.In triangle ABC, angle A = 22° and angle B = 38°. What is angle C (in degrees)?
  14. 14.The two interior opposite angles of a triangle are 33° and 21°. What is the exterior angle (in degrees)?
  15. 15.Can a triangle have sides of 11 cm, 10 cm and 11 cm? (a) Yes (b) No
  16. 16.In an isosceles triangle, the angle between the two equal sides is 84°. What is each of the other two angles (in degrees)?
  17. 17.The two interior opposite angles of a triangle are 75° and 58°. What is the exterior angle (in degrees)?
  18. 18.In an isosceles triangle, the angle between the two equal sides is 82°. What is each of the other two angles (in degrees)?
  19. 19.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  20. 20.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  21. 21.Can a triangle have sides of 9 cm, 11 cm and 8 cm? (a) Yes (b) No
  22. 22.In a right-angled triangle, one of the other two angles is 63°. What is the third angle (in degrees)?
  23. 23.In a right-angled triangle, one of the other two angles is 46°. What is the third angle (in degrees)?
  24. 24.In a right-angled triangle, one of the other two angles is 27°. What is the third angle (in degrees)?
  25. 25.In an isosceles triangle, the two equal angles are 57° each. What is the third angle (in degrees)?
  26. 26.In triangle ABC, angle A = 71° and angle B = 25°. What is angle C (in degrees)?
  27. 27.In triangle ABC, angle A = 33° and angle B = 53°. What is angle C (in degrees)?
  28. 28.In an isosceles triangle, the two equal angles are 66° each. What is the third angle (in degrees)?
  29. 29.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  30. 30.In triangle ABC, angle A = 38° and angle B = 56°. What is angle C (in degrees)?
  31. 31.In an isosceles triangle, the angle between the two equal sides is 72°. What is each of the other two angles (in degrees)?
  32. 32.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  33. 33.In an isosceles triangle, the angle between the two equal sides is 48°. What is each of the other two angles (in degrees)?
  34. 34.The two interior opposite angles of a triangle are 23° and 68°. What is the exterior angle (in degrees)?
  35. 35.The two interior opposite angles of a triangle are 76° and 29°. What is the exterior angle (in degrees)?
  36. 36.The two shorter sides of a right-angled triangle are 9 cm and 12 cm. How long is the longest side (in cm)?
  37. 37.In triangle ABC, angle A = 42° and angle B = 55°. What is angle C (in degrees)?
  38. 38.In a right-angled triangle, one of the other two angles is 55°. What is the third angle (in degrees)?
  39. 39.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  40. 40.The two interior opposite angles of a triangle are 57° and 55°. What is the exterior angle (in degrees)?

Answer key

  1. 50
  2. No
  3. 67
  4. 81
  5. 10
  6. 49
  7. No
  8. 15
  9. 16
  10. No
  11. 73
  12. 56
  13. 120
  14. 54
  15. Yes
  16. 48
  17. 133
  18. 49
  19. 25
  20. 40
  21. Yes
  22. 27
  23. 44
  24. 63
  25. 66
  26. 84
  27. 94
  28. 48
  29. 72
  30. 86
  31. 54
  32. 17
  33. 66
  34. 91
  35. 105
  36. 15
  37. 83
  38. 35
  39. 90
  40. 112

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