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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 326 · 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.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)?
  2. 2.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  3. 3.The two interior opposite angles of a triangle are 68° and 24°. What is the exterior angle (in degrees)?
  4. 4.Can a triangle have sides of 23 cm, 10 cm and 11 cm? (a) Yes (b) No
  5. 5.In triangle ABC, angle A = 63° and angle B = 35°. What is angle C (in degrees)?
  6. 6.In a right-angled triangle, one of the other two angles is 22°. What is the third angle (in degrees)?
  7. 7.In triangle ABC, angle A = 44° and angle B = 33°. What is angle C (in degrees)?
  8. 8.Can a triangle have sides of 12 cm, 15 cm and 5 cm? (a) Yes (b) No
  9. 9.In triangle ABC, angle A = 47° and angle B = 27°. What is angle C (in degrees)?
  10. 10.In an isosceles triangle, the two equal angles are 24° each. What is the third angle (in degrees)?
  11. 11.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (in degrees)?
  12. 12.An exterior angle of a triangle is 88°. One of its two interior opposite angles is 37°. What is the other one (in degrees)?
  13. 13.Can a triangle have sides of 6 cm, 9 cm and 4 cm? (a) No (b) Yes
  14. 14.The two interior opposite angles of a triangle are 72° and 34°. What is the exterior angle (in degrees)?
  15. 15.An exterior angle of a triangle is 110°. One of its two interior opposite angles is 72°. What is the other one (in degrees)?
  16. 16.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  17. 17.Can a triangle have sides of 10 cm, 16 cm and 11 cm? (a) Yes (b) No
  18. 18.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  19. 19.In triangle ABC, angle A = 23° and angle B = 90°. What is angle C (in degrees)?
  20. 20.In an isosceles triangle, the angle between the two equal sides is 114°. What is each of the other two angles (in degrees)?
  21. 21.In triangle ABC, angle A = 49° and angle B = 50°. What is angle C (in degrees)?
  22. 22.In triangle ABC, angle A = 79° and angle B = 27°. What is angle C (in degrees)?
  23. 23.The longest side of a right-angled triangle is 25 cm and one of the other sides is 24 cm. How long is the third side (in cm)?
  24. 24.In triangle ABC, angle A = 67° and angle B = 90°. What is angle C (in degrees)?
  25. 25.Can a triangle have sides of 8 cm, 8 cm and 8 cm? (a) Yes (b) No
  26. 26.In triangle ABC, angle A = 91° and angle B = 52°. What is angle C (in degrees)?
  27. 27.An exterior angle of a triangle is 64°. One of its two interior opposite angles is 41°. What is the other one (in degrees)?
  28. 28.Can a triangle have sides of 7 cm, 8 cm and 2 cm? (a) Yes (b) No
  29. 29.An exterior angle of a triangle is 87°. One of its two interior opposite angles is 27°. What is the other one (in degrees)?
  30. 30.In a right-angled triangle, one of the other two angles is 49°. What is the third angle (in degrees)?
  31. 31.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  32. 32.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  33. 33.An exterior angle of a triangle is 45°. One of its two interior opposite angles is 22°. What is the other one (in degrees)?
  34. 34.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?
  35. 35.Can a triangle have sides of 5 cm, 11 cm and 17 cm? (a) No (b) Yes
  36. 36.Can a triangle have sides of 8 cm, 20 cm and 8 cm? (a) No (b) Yes
  37. 37.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)?
  38. 38.An exterior angle of a triangle is 126°. One of its two interior opposite angles is 62°. What is the other one (in degrees)?
  39. 39.The two shorter sides of a right-angled triangle are 12 cm and 5 cm. How long is the longest side (in cm)?
  40. 40.Can a triangle have sides of 9 cm, 13 cm and 3 cm? (a) Yes (b) No

Answer key

  1. 6
  2. 17
  3. 92
  4. No
  5. 82
  6. 68
  7. 103
  8. Yes
  9. 106
  10. 132
  11. 72
  12. 51
  13. Yes
  14. 106
  15. 38
  16. 20
  17. Yes
  18. 90
  19. 67
  20. 33
  21. 81
  22. 74
  23. 7
  24. 23
  25. Yes
  26. 37
  27. 23
  28. Yes
  29. 60
  30. 41
  31. 25
  32. 72
  33. 23
  34. 48
  35. No
  36. No
  37. 10
  38. 64
  39. 13
  40. No

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