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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 789 · 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.An exterior angle of a triangle is 132°. One of its two interior opposite angles is 79°. What is the other one (in degrees)?
  2. 2.In a right-angled triangle, one of the other two angles is 57°. What is the third angle (in degrees)?
  3. 3.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  4. 4.Can a triangle have sides of 7 cm, 4 cm and 4 cm? (a) No (b) Yes
  5. 5.In a right-angled triangle, one of the other two angles is 32°. What is the third angle (in degrees)?
  6. 6.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  7. 7.In an isosceles triangle, the angle between the two equal sides is 92°. What is each of the other two angles (in degrees)?
  8. 8.The angles of a triangle are in the ratio 3 : 5 : 7. What is the biggest angle (in degrees)?
  9. 9.The longest side of a right-angled triangle is 20 cm and one of the other sides is 16 cm. How long is the third side (in cm)?
  10. 10.Can a triangle have sides of 6 cm, 6 cm and 12 cm? (a) Yes (b) No
  11. 11.Can a triangle have sides of 9 cm, 5 cm and 3 cm? (a) No (b) Yes
  12. 12.An exterior angle of a triangle is 79°. One of its two interior opposite angles is 56°. What is the other one (in degrees)?
  13. 13.In an isosceles triangle, the angle between the two equal sides is 120°. What is each of the other two angles (in degrees)?
  14. 14.In an isosceles triangle, the angle between the two equal sides is 144°. What is each of the other two angles (in degrees)?
  15. 15.In triangle ABC, angle A = 35° and angle B = 38°. What is angle C (in degrees)?
  16. 16.The two interior opposite angles of a triangle are 34° and 59°. What is the exterior angle (in degrees)?
  17. 17.In an isosceles triangle, the angle between the two equal sides is 114°. What is each of the other two angles (in degrees)?
  18. 18.The longest side of a right-angled triangle is 25 cm and one of the other sides is 20 cm. How long is the third side (in cm)?
  19. 19.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  20. 20.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  21. 21.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  22. 22.The two interior opposite angles of a triangle are 59° and 53°. What is the exterior angle (in degrees)?
  23. 23.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  24. 24.The two shorter sides of a right-angled triangle are 12 cm and 9 cm. How long is the longest side (in cm)?
  25. 25.The two shorter sides of a right-angled triangle are 15 cm and 20 cm. How long is the longest side (in cm)?
  26. 26.In triangle ABC, angle A = 48° and angle B = 36°. What is angle C (in degrees)?
  27. 27.In triangle ABC, angle A = 54° and angle B = 24°. What is angle C (in degrees)?
  28. 28.In triangle ABC, angle A = 43° and angle B = 32°. What is angle C (in degrees)?
  29. 29.In a right-angled triangle, one of the other two angles is 19°. What is the third angle (in degrees)?
  30. 30.In an isosceles triangle, the two equal angles are 54° each. 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.In an isosceles triangle, the angle between the two equal sides is 56°. What is each of the other two angles (in degrees)?
  33. 33.The two interior opposite angles of a triangle are 51° and 65°. What is the exterior angle (in degrees)?
  34. 34.The two interior opposite angles of a triangle are 31° and 37°. What is the exterior angle (in degrees)?
  35. 35.In triangle ABC, angle A = 30° and angle B = 76°. What is angle C (in degrees)?
  36. 36.In triangle ABC, angle A = 49° and angle B = 40°. What is angle C (in degrees)?
  37. 37.Can a triangle have sides of 9 cm, 4 cm and 18 cm? (a) No (b) Yes
  38. 38.In a right-angled triangle, one of the other two angles is 12°. What is the third angle (in degrees)?
  39. 39.In triangle ABC, angle A = 92° and angle B = 30°. What is angle C (in degrees)?
  40. 40.Can a triangle have sides of 4 cm, 2 cm and 5 cm? (a) Yes (b) No

Answer key

  1. 53
  2. 33
  3. 20
  4. Yes
  5. 58
  6. 36
  7. 44
  8. 84
  9. 12
  10. No
  11. No
  12. 23
  13. 30
  14. 18
  15. 107
  16. 93
  17. 33
  18. 15
  19. 90
  20. 100
  21. 100
  22. 112
  23. 17
  24. 15
  25. 25
  26. 96
  27. 102
  28. 105
  29. 71
  30. 72
  31. 25
  32. 62
  33. 116
  34. 68
  35. 74
  36. 91
  37. No
  38. 78
  39. 58
  40. Yes

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