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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 249 · 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 two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  2. 2.Can a triangle have sides of 4 cm, 4 cm and 4 cm? (a) Yes (b) No
  3. 3.The angles of a triangle are in the ratio 2 : 2 : 5. What is the smallest angle (in degrees)?
  4. 4.In a right-angled triangle, one of the other two angles is 67°. What is the third angle (in degrees)?
  5. 5.In triangle ABC, angle A = 72° and angle B = 60°. What is angle C (in degrees)?
  6. 6.In an isosceles triangle, the two equal angles are 30° each. What is the third angle (in degrees)?
  7. 7.In a right-angled triangle, one of the other two angles is 17°. What is the third angle (in degrees)?
  8. 8.Can a triangle have sides of 25 cm, 12 cm and 8 cm? (a) Yes (b) No
  9. 9.In an isosceles triangle, the angle between the two equal sides is 68°. What is each of the other two angles (in degrees)?
  10. 10.In triangle ABC, angle A = 20° and angle B = 98°. What is angle C (in degrees)?
  11. 11.Can a triangle have sides of 13 cm, 6 cm and 7 cm? (a) No (b) Yes
  12. 12.Can a triangle have sides of 15 cm, 12 cm and 6 cm? (a) Yes (b) No
  13. 13.Can a triangle have sides of 6 cm, 5 cm and 4 cm? (a) No (b) Yes
  14. 14.In a right-angled triangle, one of the other two angles is 16°. What is the third angle (in degrees)?
  15. 15.The two shorter sides of a right-angled triangle are 15 cm and 20 cm. How long is the longest side (in cm)?
  16. 16.The two interior opposite angles of a triangle are 39° and 73°. What is the exterior angle (in degrees)?
  17. 17.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)?
  18. 18.In triangle ABC, angle A = 80° and angle B = 32°. What is angle C (in degrees)?
  19. 19.Can a triangle have sides of 3 cm, 3 cm and 8 cm? (a) Yes (b) No
  20. 20.In an isosceles triangle, the two equal angles are 72° each. What is the third angle (in degrees)?
  21. 21.Can a triangle have sides of 10 cm, 12 cm and 25 cm? (a) No (b) Yes
  22. 22.In an isosceles triangle, the two equal angles are 52° each. What is the third angle (in degrees)?
  23. 23.The longest side of a right-angled triangle is 13 cm and one of the other sides is 12 cm. How long is the third side (in cm)?
  24. 24.An exterior angle of a triangle is 123°. One of its two interior opposite angles is 56°. What is the other one (in degrees)?
  25. 25.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  26. 26.In an isosceles triangle, the two equal angles are 79° each. What is the third angle (in degrees)?
  27. 27.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  28. 28.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  29. 29.In triangle ABC, angle A = 82° and angle B = 56°. What is angle C (in degrees)?
  30. 30.Can a triangle have sides of 9 cm, 2 cm and 6 cm? (a) Yes (b) No
  31. 31.Can a triangle have sides of 12 cm, 5 cm and 13 cm? (a) Yes (b) No
  32. 32.In an isosceles triangle, the two equal angles are 66° each. What is the third angle (in degrees)?
  33. 33.Can a triangle have sides of 12 cm, 12 cm and 2 cm? (a) No (b) Yes
  34. 34.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  35. 35.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  36. 36.In a right-angled triangle, one of the other two angles is 59°. What is the third angle (in degrees)?
  37. 37.Can a triangle have sides of 8 cm, 10 cm and 10 cm? (a) Yes (b) No
  38. 38.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (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.The two interior opposite angles of a triangle are 65° and 43°. What is the exterior angle (in degrees)?

Answer key

  1. 39
  2. Yes
  3. 40
  4. 23
  5. 48
  6. 120
  7. 73
  8. No
  9. 56
  10. 62
  11. No
  12. Yes
  13. Yes
  14. 74
  15. 25
  16. 112
  17. 15
  18. 68
  19. No
  20. 36
  21. No
  22. 76
  23. 5
  24. 67
  25. 90
  26. 22
  27. 40
  28. 90
  29. 42
  30. No
  31. Yes
  32. 48
  33. Yes
  34. 45
  35. 36
  36. 31
  37. Yes
  38. 72
  39. 13
  40. 108

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