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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 428 · 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 interior opposite angles of a triangle are 63° and 56°. What is the exterior angle (in degrees)?
  2. 2.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  3. 3.The longest side of a right-angled triangle is 10 cm and one of the other sides is 6 cm. How long is the third side (in cm)?
  4. 4.An exterior angle of a triangle is 88°. One of its two interior opposite angles is 55°. What is the other one (in degrees)?
  5. 5.The angles of a triangle are in the ratio 5 : 6 : 7. What is the biggest angle (in degrees)?
  6. 6.Can a triangle have sides of 3 cm, 3 cm and 3 cm? (a) No (b) Yes
  7. 7.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)?
  8. 8.In triangle ABC, angle A = 27° and angle B = 66°. What is angle C (in degrees)?
  9. 9.In an isosceles triangle, the angle between the two equal sides is 60°. What is each of the other two angles (in degrees)?
  10. 10.The longest side of a right-angled triangle is 5 cm and one of the other sides is 4 cm. How long is the third side (in cm)?
  11. 11.Can a triangle have sides of 11 cm, 3 cm and 3 cm? (a) Yes (b) No
  12. 12.In triangle ABC, angle A = 58° and angle B = 61°. What is angle C (in degrees)?
  13. 13.In a right-angled triangle, one of the other two angles is 70°. What is the third angle (in degrees)?
  14. 14.The two shorter sides of a right-angled triangle are 5 cm and 12 cm. How long is the longest side (in cm)?
  15. 15.In a right-angled triangle, one of the other two angles is 11°. What is the third angle (in degrees)?
  16. 16.In a right-angled triangle, one of the other two angles is 54°. What is the third angle (in degrees)?
  17. 17.In an isosceles triangle, the angle between the two equal sides is 50°. What is each of the other two angles (in degrees)?
  18. 18.An exterior angle of a triangle is 126°. One of its two interior opposite angles is 63°. What is the other one (in degrees)?
  19. 19.In a right-angled triangle, one of the other two angles is 27°. What is the third angle (in degrees)?
  20. 20.In triangle ABC, angle A = 60° and angle B = 78°. What is angle C (in degrees)?
  21. 21.In an isosceles triangle, the two equal angles are 30° each. What is the third angle (in degrees)?
  22. 22.The two interior opposite angles of a triangle are 41° and 37°. What is the exterior angle (in degrees)?
  23. 23.An exterior angle of a triangle is 104°. One of its two interior opposite angles is 25°. What is the other one (in degrees)?
  24. 24.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  25. 25.The angles of a triangle are in the ratio 1 : 2 : 3. What is the smallest angle (in degrees)?
  26. 26.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?
  27. 27.The angles of a triangle are in the ratio 1 : 2 : 2. What is the smallest angle (in degrees)?
  28. 28.The two shorter sides of a right-angled triangle are 6 cm and 8 cm. How long is the longest side (in cm)?
  29. 29.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  30. 30.Can a triangle have sides of 6 cm, 7 cm and 5 cm? (a) No (b) Yes
  31. 31.In triangle ABC, angle A = 23° and angle B = 86°. What is angle C (in degrees)?
  32. 32.In an isosceles triangle, the angle between the two equal sides is 104°. What is each of the other two angles (in degrees)?
  33. 33.In triangle ABC, angle A = 58° and angle B = 59°. What is angle C (in degrees)?
  34. 34.The two shorter sides of a right-angled triangle are 12 cm and 16 cm. How long is the longest side (in cm)?
  35. 35.In triangle ABC, angle A = 30° and angle B = 73°. What is angle C (in degrees)?
  36. 36.An exterior angle of a triangle is 113°. One of its two interior opposite angles is 72°. What is the other one (in degrees)?
  37. 37.In a right-angled triangle, one of the other two angles is 58°. What is the third angle (in degrees)?
  38. 38.Can a triangle have sides of 3 cm, 14 cm and 12 cm? (a) No (b) Yes
  39. 39.In a right-angled triangle, one of the other two angles is 53°. What is the third angle (in degrees)?
  40. 40.The longest side of a right-angled triangle is 15 cm and one of the other sides is 12 cm. How long is the third side (in cm)?

Answer key

  1. 119
  2. 120
  3. 8
  4. 33
  5. 70
  6. Yes
  7. 24
  8. 87
  9. 60
  10. 3
  11. No
  12. 61
  13. 20
  14. 13
  15. 79
  16. 36
  17. 65
  18. 63
  19. 63
  20. 42
  21. 120
  22. 78
  23. 79
  24. 90
  25. 30
  26. 50
  27. 36
  28. 10
  29. 100
  30. Yes
  31. 71
  32. 38
  33. 63
  34. 20
  35. 77
  36. 41
  37. 32
  38. Yes
  39. 37
  40. 9

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