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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 561 · 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.

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  1. 1.In triangle ABC, angle A = 41° and angle B = 117°. What is angle C (in degrees)?
  2. 2.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  3. 3.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  4. 4.Can a triangle have sides of 11 cm, 9 cm and 8 cm? (a) No (b) Yes
  5. 5.The angles of a triangle are in the ratio 3 : 3 : 4. What is the smallest angle (in degrees)?
  6. 6.An exterior angle of a triangle is 103°. One of its two interior opposite angles is 58°. What is the other one (in degrees)?
  7. 7.In a right-angled triangle, one of the other two angles is 10°. What is the third angle (in degrees)?
  8. 8.Can a triangle have sides of 2 cm, 5 cm and 4 cm? (a) Yes (b) No
  9. 9.The angles of a triangle are in the ratio 1 : 2 : 2. What is the smallest angle (in degrees)?
  10. 10.In triangle ABC, angle A = 30° and angle B = 27°. What is angle C (in degrees)?
  11. 11.In triangle ABC, angle A = 32° and angle B = 54°. What is angle C (in degrees)?
  12. 12.Can a triangle have sides of 6 cm, 5 cm and 3 cm? (a) No (b) Yes
  13. 13.The angles of a triangle are in the ratio 1 : 2 : 3. What is the biggest angle (in degrees)?
  14. 14.In a right-angled triangle, one of the other two angles is 43°. What is the third angle (in degrees)?
  15. 15.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  16. 16.An exterior angle of a triangle is 60°. One of its two interior opposite angles is 26°. What is the other one (in degrees)?
  17. 17.An exterior angle of a triangle is 73°. One of its two interior opposite angles is 36°. What is the other one (in degrees)?
  18. 18.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  19. 19.In an isosceles triangle, the two equal angles are 27° each. What is the third angle (in degrees)?
  20. 20.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  21. 21.The angles of a triangle are in the ratio 5 : 6 : 7. What is the biggest angle (in degrees)?
  22. 22.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  23. 23.An exterior angle of a triangle is 80°. One of its two interior opposite angles is 57°. What is the other one (in degrees)?
  24. 24.An exterior angle of a triangle is 100°. One of its two interior opposite angles is 43°. What is the other one (in degrees)?
  25. 25.In an isosceles triangle, the two equal angles are 54° each. What is the third angle (in degrees)?
  26. 26.Can a triangle have sides of 12 cm, 8 cm and 25 cm? (a) Yes (b) No
  27. 27.An exterior angle of a triangle is 58°. One of its two interior opposite angles is 34°. What is the other one (in degrees)?
  28. 28.In a right-angled triangle, one of the other two angles is 71°. What is the third angle (in degrees)?
  29. 29.Can a triangle have sides of 7 cm, 2 cm and 6 cm? (a) No (b) Yes
  30. 30.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  31. 31.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  32. 32.The longest side of a right-angled triangle is 26 cm and one of the other sides is 10 cm. How long is the third side (in cm)?
  33. 33.In triangle ABC, angle A = 47° and angle B = 63°. What is angle C (in degrees)?
  34. 34.In an isosceles triangle, the two equal angles are 51° each. What is the third angle (in degrees)?
  35. 35.In triangle ABC, angle A = 97° and angle B = 41°. What is angle C (in degrees)?
  36. 36.In triangle ABC, angle A = 35° and angle B = 48°. What is angle C (in degrees)?
  37. 37.In triangle ABC, angle A = 87° and angle B = 64°. What is angle C (in degrees)?
  38. 38.In triangle ABC, angle A = 31° and angle B = 109°. What is angle C (in degrees)?
  39. 39.In an isosceles triangle, the angle between the two equal sides is 108°. What is each of the other two angles (in degrees)?
  40. 40.Can a triangle have sides of 4 cm, 8 cm and 16 cm? (a) Yes (b) No

Answer key

  1. 22
  2. 100
  3. 20
  4. Yes
  5. 54
  6. 45
  7. 80
  8. Yes
  9. 36
  10. 123
  11. 94
  12. Yes
  13. 90
  14. 47
  15. 120
  16. 34
  17. 37
  18. 72
  19. 126
  20. 25
  21. 70
  22. 90
  23. 23
  24. 57
  25. 72
  26. No
  27. 24
  28. 19
  29. Yes
  30. 75
  31. 17
  32. 24
  33. 70
  34. 78
  35. 42
  36. 97
  37. 29
  38. 40
  39. 36
  40. No

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