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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 926 · 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 angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  2. 2.In triangle ABC, angle A = 70° and angle B = 64°. What is angle C (in degrees)?
  3. 3.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?
  4. 4.Can a triangle have sides of 2 cm, 6 cm and 12 cm? (a) Yes (b) No
  5. 5.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)?
  6. 6.In an isosceles triangle, the angle between the two equal sides is 44°. What is each of the other two angles (in degrees)?
  7. 7.The two interior opposite angles of a triangle are 77° and 41°. What is the exterior angle (in degrees)?
  8. 8.In triangle ABC, angle A = 28° and angle B = 28°. What is angle C (in degrees)?
  9. 9.The two interior opposite angles of a triangle are 24° and 56°. What is the exterior angle (in degrees)?
  10. 10.In triangle ABC, angle A = 62° and angle B = 41°. What is angle C (in degrees)?
  11. 11.In a right-angled triangle, one of the other two angles is 59°. What is the third angle (in degrees)?
  12. 12.An exterior angle of a triangle is 80°. One of its two interior opposite angles is 59°. What is the other one (in degrees)?
  13. 13.Can a triangle have sides of 6 cm, 11 cm and 10 cm? (a) Yes (b) No
  14. 14.Can a triangle have sides of 10 cm, 3 cm and 13 cm? (a) No (b) Yes
  15. 15.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)?
  16. 16.In an isosceles triangle, the angle between the two equal sides is 152°. What is each of the other two angles (in degrees)?
  17. 17.An exterior angle of a triangle is 113°. One of its two interior opposite angles is 79°. What is the other one (in degrees)?
  18. 18.In a right-angled triangle, one of the other two angles is 34°. What is the third angle (in degrees)?
  19. 19.In an isosceles triangle, the angle between the two equal sides is 30°. What is each of the other two angles (in degrees)?
  20. 20.In a right-angled triangle, one of the other two angles is 57°. What is the third angle (in degrees)?
  21. 21.The two interior opposite angles of a triangle are 27° and 47°. What is the exterior angle (in degrees)?
  22. 22.In a right-angled triangle, one of the other two angles is 26°. What is the third angle (in degrees)?
  23. 23.In triangle ABC, angle A = 94° and angle B = 41°. What is angle C (in degrees)?
  24. 24.Can a triangle have sides of 11 cm, 5 cm and 9 cm? (a) Yes (b) No
  25. 25.Can a triangle have sides of 14 cm, 8 cm and 8 cm? (a) Yes (b) No
  26. 26.An exterior angle of a triangle is 92°. One of its two interior opposite angles is 38°. What is the other one (in degrees)?
  27. 27.Can a triangle have sides of 11 cm, 4 cm and 3 cm? (a) No (b) Yes
  28. 28.The two interior opposite angles of a triangle are 67° and 59°. What is the exterior angle (in degrees)?
  29. 29.In triangle ABC, angle A = 20° and angle B = 88°. What is angle C (in degrees)?
  30. 30.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  31. 31.The angles of a triangle are in the ratio 2 : 2 : 5. What is the smallest angle (in degrees)?
  32. 32.In a right-angled triangle, one of the other two angles is 12°. What is the third angle (in degrees)?
  33. 33.An exterior angle of a triangle is 89°. One of its two interior opposite angles is 45°. What is the other one (in degrees)?
  34. 34.An exterior angle of a triangle is 102°. One of its two interior opposite angles is 62°. What is the other one (in degrees)?
  35. 35.In an isosceles triangle, the angle between the two equal sides is 130°. What is each of the other two angles (in degrees)?
  36. 36.The longest side of a right-angled triangle is 5 cm and one of the other sides is 3 cm. How long is the third side (in cm)?
  37. 37.The two interior opposite angles of a triangle are 63° and 77°. What is the exterior angle (in degrees)?
  38. 38.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  39. 39.In a right-angled triangle, one of the other two angles is 28°. What is the third angle (in degrees)?
  40. 40.Can a triangle have sides of 13 cm, 4 cm and 4 cm? (a) Yes (b) No

Answer key

  1. 120
  2. 46
  3. 50
  4. No
  5. 24
  6. 68
  7. 118
  8. 124
  9. 80
  10. 77
  11. 31
  12. 21
  13. Yes
  14. No
  15. 3
  16. 14
  17. 34
  18. 56
  19. 75
  20. 33
  21. 74
  22. 64
  23. 45
  24. Yes
  25. Yes
  26. 54
  27. No
  28. 126
  29. 72
  30. 100
  31. 40
  32. 78
  33. 44
  34. 40
  35. 25
  36. 4
  37. 140
  38. 80
  39. 62
  40. No

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