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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 770 · 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 7 cm and 24 cm. How long is the longest side (in cm)?
  2. 2.The longest side of a right-angled triangle is 25 cm and one of the other sides is 7 cm. How long is the third side (in cm)?
  3. 3.In a right-angled triangle, one of the other two angles is 35°. What is the third angle (in degrees)?
  4. 4.The two interior opposite angles of a triangle are 77° and 28°. What is the exterior angle (in degrees)?
  5. 5.The two interior opposite angles of a triangle are 67° and 21°. What is the exterior angle (in degrees)?
  6. 6.An exterior angle of a triangle is 91°. One of its two interior opposite angles is 46°. What is the other one (in degrees)?
  7. 7.The longest side of a right-angled triangle is 39 cm and one of the other sides is 36 cm. How long is the third side (in cm)?
  8. 8.In triangle ABC, angle A = 80° and angle B = 24°. What is angle C (in degrees)?
  9. 9.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  10. 10.In a right-angled triangle, one of the other two angles is 30°. What is the third angle (in degrees)?
  11. 11.In an isosceles triangle, the angle between the two equal sides is 48°. What is each of the other two angles (in degrees)?
  12. 12.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?
  13. 13.In triangle ABC, angle A = 61° and angle B = 60°. What is angle C (in degrees)?
  14. 14.Can a triangle have sides of 11 cm, 15 cm and 4 cm? (a) Yes (b) No
  15. 15.An exterior angle of a triangle is 101°. One of its two interior opposite angles is 57°. What is the other one (in degrees)?
  16. 16.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  17. 17.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  18. 18.In an isosceles triangle, the two equal angles are 50° each. What is the third angle (in degrees)?
  19. 19.In a right-angled triangle, one of the other two angles is 63°. What is the third angle (in degrees)?
  20. 20.The two shorter sides of a right-angled triangle are 3 cm and 4 cm. How long is the longest side (in cm)?
  21. 21.Can a triangle have sides of 5 cm, 18 cm and 10 cm? (a) Yes (b) No
  22. 22.The two shorter sides of a right-angled triangle are 24 cm and 10 cm. How long is the longest side (in cm)?
  23. 23.Can a triangle have sides of 9 cm, 9 cm and 7 cm? (a) No (b) Yes
  24. 24.The two shorter sides of a right-angled triangle are 18 cm and 24 cm. How long is the longest side (in cm)?
  25. 25.The two interior opposite angles of a triangle are 58° and 49°. What is the exterior angle (in degrees)?
  26. 26.An exterior angle of a triangle is 118°. One of its two interior opposite angles is 74°. What is the other one (in degrees)?
  27. 27.In an isosceles triangle, the two equal angles are 36° each. What is the third angle (in degrees)?
  28. 28.The two interior opposite angles of a triangle are 71° and 33°. What is the exterior angle (in degrees)?
  29. 29.In a right-angled triangle, one of the other two angles is 33°. What is the third angle (in degrees)?
  30. 30.An exterior angle of a triangle is 85°. One of its two interior opposite angles is 31°. What is the other one (in degrees)?
  31. 31.The two interior opposite angles of a triangle are 30° and 52°. What is the exterior angle (in degrees)?
  32. 32.In triangle ABC, angle A = 44° and angle B = 91°. What is angle C (in degrees)?
  33. 33.The two interior opposite angles of a triangle are 44° and 49°. What is the exterior angle (in degrees)?
  34. 34.An exterior angle of a triangle is 92°. One of its two interior opposite angles is 68°. What is the other one (in degrees)?
  35. 35.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  36. 36.Can a triangle have sides of 13 cm, 2 cm and 10 cm? (a) Yes (b) No
  37. 37.In triangle ABC, angle A = 47° and angle B = 43°. What is angle C (in degrees)?
  38. 38.In a right-angled triangle, one of the other two angles is 67°. What is the third angle (in degrees)?
  39. 39.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  40. 40.In an isosceles triangle, the angle between the two equal sides is 30°. What is each of the other two angles (in degrees)?

Answer key

  1. 25
  2. 24
  3. 55
  4. 105
  5. 88
  6. 45
  7. 15
  8. 76
  9. 25
  10. 60
  11. 66
  12. 50
  13. 59
  14. No
  15. 44
  16. 20
  17. 100
  18. 80
  19. 27
  20. 5
  21. No
  22. 26
  23. Yes
  24. 30
  25. 107
  26. 44
  27. 108
  28. 104
  29. 57
  30. 54
  31. 82
  32. 45
  33. 93
  34. 24
  35. 100
  36. No
  37. 90
  38. 23
  39. 90
  40. 75

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