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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 977 · 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 = 66° and angle B = 62°. What is angle C (in degrees)?
  2. 2.Can a triangle have sides of 5 cm, 4 cm and 11 cm? (a) Yes (b) No
  3. 3.The angles of a triangle are in the ratio 5 : 6 : 7. What is the biggest angle (in degrees)?
  4. 4.In an isosceles triangle, the two equal angles are 39° 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 biggest angle (in degrees)?
  6. 6.In triangle ABC, angle A = 38° and angle B = 100°. What is angle C (in degrees)?
  7. 7.In a right-angled triangle, one of the other two angles is 37°. What is the third angle (in degrees)?
  8. 8.In triangle ABC, angle A = 25° and angle B = 25°. What is angle C (in degrees)?
  9. 9.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  10. 10.In a right-angled triangle, one of the other two angles is 54°. What is the third angle (in degrees)?
  11. 11.In triangle ABC, angle A = 75° and angle B = 39°. What is angle C (in degrees)?
  12. 12.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  13. 13.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  14. 14.An exterior angle of a triangle is 95°. One of its two interior opposite angles is 48°. What is the other one (in degrees)?
  15. 15.The longest side of a right-angled triangle is 30 cm and one of the other sides is 24 cm. How long is the third side (in cm)?
  16. 16.In a right-angled triangle, one of the other two angles is 22°. What is the third angle (in degrees)?
  17. 17.In triangle ABC, angle A = 29° and angle B = 93°. What is angle C (in degrees)?
  18. 18.Can a triangle have sides of 18 cm, 10 cm and 3 cm? (a) Yes (b) No
  19. 19.The two interior opposite angles of a triangle are 59° and 40°. What is the exterior angle (in degrees)?
  20. 20.The two shorter sides of a right-angled triangle are 12 cm and 5 cm. How long is the longest side (in cm)?
  21. 21.The angles of a triangle are in the ratio 3 : 5 : 7. What is the biggest angle (in degrees)?
  22. 22.In triangle ABC, angle A = 26° and angle B = 52°. What is angle C (in degrees)?
  23. 23.In an isosceles triangle, the two equal angles are 51° each. What is the third angle (in degrees)?
  24. 24.In triangle ABC, angle A = 31° and angle B = 86°. What is angle C (in degrees)?
  25. 25.In an isosceles triangle, the angle between the two equal sides is 34°. What is each of the other two angles (in degrees)?
  26. 26.The two interior opposite angles of a triangle are 27° and 32°. What is the exterior angle (in degrees)?
  27. 27.In triangle ABC, angle A = 20° and angle B = 112°. What is angle C (in degrees)?
  28. 28.In an isosceles triangle, the angle between the two equal sides is 62°. What is each of the other two angles (in degrees)?
  29. 29.In an isosceles triangle, the two equal angles are 64° each. What is the third angle (in degrees)?
  30. 30.In an isosceles triangle, the angle between the two equal sides is 76°. What is each of the other two angles (in degrees)?
  31. 31.In an isosceles triangle, the angle between the two equal sides is 50°. What is each of the other two angles (in degrees)?
  32. 32.The longest side of a right-angled triangle is 20 cm and one of the other sides is 16 cm. How long is the third side (in cm)?
  33. 33.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  34. 34.In an isosceles triangle, the angle between the two equal sides is 128°. What is each of the other two angles (in degrees)?
  35. 35.In a right-angled triangle, one of the other two angles is 56°. What is the third angle (in degrees)?
  36. 36.The two shorter sides of a right-angled triangle are 16 cm and 12 cm. How long is the longest side (in cm)?
  37. 37.Can a triangle have sides of 8 cm, 11 cm and 3 cm? (a) No (b) Yes
  38. 38.An exterior angle of a triangle is 110°. One of its two interior opposite angles is 37°. What is the other one (in degrees)?
  39. 39.In a right-angled triangle, one of the other two angles is 39°. What is the third angle (in degrees)?
  40. 40.In an isosceles triangle, the two equal angles are 44° each. What is the third angle (in degrees)?

Answer key

  1. 52
  2. No
  3. 70
  4. 102
  5. 72
  6. 42
  7. 53
  8. 130
  9. 17
  10. 36
  11. 66
  12. 80
  13. 120
  14. 47
  15. 18
  16. 68
  17. 58
  18. No
  19. 99
  20. 13
  21. 84
  22. 102
  23. 78
  24. 63
  25. 73
  26. 59
  27. 48
  28. 59
  29. 52
  30. 52
  31. 65
  32. 12
  33. 90
  34. 26
  35. 34
  36. 20
  37. No
  38. 73
  39. 51
  40. 92

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