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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 273 · 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.

NameDateTime takenScore ___ / 40
  1. 1.Can a triangle have sides of 3 cm, 6 cm and 5 cm? (a) Yes (b) No
  2. 2.An exterior angle of a triangle is 93°. One of its two interior opposite angles is 41°. What is the other one (in degrees)?
  3. 3.The two interior opposite angles of a triangle are 21° and 33°. What is the exterior angle (in degrees)?
  4. 4.Can a triangle have sides of 8 cm, 11 cm and 19 cm? (a) Yes (b) No
  5. 5.An exterior angle of a triangle is 121°. One of its two interior opposite angles is 49°. What is the other one (in degrees)?
  6. 6.Can a triangle have sides of 12 cm, 20 cm and 7 cm? (a) Yes (b) No
  7. 7.The angles of a triangle are in the ratio 3 : 3 : 4. What is the smallest angle (in degrees)?
  8. 8.The angles of a triangle are in the ratio 1 : 2 : 3. What is the smallest angle (in degrees)?
  9. 9.In an isosceles triangle, the angle between the two equal sides is 40°. What is each of the other two angles (in degrees)?
  10. 10.The two interior opposite angles of a triangle are 75° and 27°. What is the exterior angle (in degrees)?
  11. 11.In an isosceles triangle, the two equal angles are 20° each. What is the third angle (in degrees)?
  12. 12.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  13. 13.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  14. 14.An exterior angle of a triangle is 48°. One of its two interior opposite angles is 26°. What is the other one (in degrees)?
  15. 15.The longest side of a right-angled triangle is 20 cm and one of the other sides is 12 cm. How long is the third side (in cm)?
  16. 16.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  17. 17.In a right-angled triangle, one of the other two angles is 51°. What is the third angle (in degrees)?
  18. 18.Can a triangle have sides of 11 cm, 5 cm and 18 cm? (a) Yes (b) No
  19. 19.In a right-angled triangle, one of the other two angles is 37°. What is the third angle (in degrees)?
  20. 20.In triangle ABC, angle A = 29° and angle B = 20°. What is angle C (in degrees)?
  21. 21.In triangle ABC, angle A = 100° and angle B = 41°. What is angle C (in degrees)?
  22. 22.In triangle ABC, angle A = 88° and angle B = 39°. What is angle C (in degrees)?
  23. 23.Can a triangle have sides of 10 cm, 6 cm and 7 cm? (a) No (b) Yes
  24. 24.In an isosceles triangle, the two equal angles are 40° each. What is the third angle (in degrees)?
  25. 25.In triangle ABC, angle A = 92° and angle B = 23°. What is angle C (in degrees)?
  26. 26.In triangle ABC, angle A = 46° and angle B = 65°. What is angle C (in degrees)?
  27. 27.In a right-angled triangle, one of the other two angles is 39°. What is the third angle (in degrees)?
  28. 28.In triangle ABC, angle A = 77° and angle B = 27°. What is angle C (in degrees)?
  29. 29.Can a triangle have sides of 8 cm, 2 cm and 2 cm? (a) Yes (b) No
  30. 30.In an isosceles triangle, the angle between the two equal sides is 44°. What is each of the other two angles (in degrees)?
  31. 31.In triangle ABC, angle A = 26° and angle B = 67°. What is angle C (in degrees)?
  32. 32.An exterior angle of a triangle is 97°. One of its two interior opposite angles is 39°. What is the other one (in degrees)?
  33. 33.In triangle ABC, angle A = 31° and angle B = 60°. What is angle C (in degrees)?
  34. 34.In a right-angled triangle, one of the other two angles is 22°. What is the third angle (in degrees)?
  35. 35.In an isosceles triangle, the two equal angles are 34° each. What is the third angle (in degrees)?
  36. 36.Can a triangle have sides of 11 cm, 21 cm and 10 cm? (a) Yes (b) No
  37. 37.The two interior opposite angles of a triangle are 79° and 40°. What is the exterior angle (in degrees)?
  38. 38.The two interior opposite angles of a triangle are 55° and 22°. What is the exterior angle (in degrees)?
  39. 39.An exterior angle of a triangle is 42°. One of its two interior opposite angles is 21°. What is the other one (in degrees)?
  40. 40.An exterior angle of a triangle is 66°. One of its two interior opposite angles is 39°. What is the other one (in degrees)?

Answer key

  1. Yes
  2. 52
  3. 54
  4. No
  5. 72
  6. No
  7. 54
  8. 30
  9. 70
  10. 102
  11. 140
  12. 100
  13. 25
  14. 22
  15. 16
  16. 90
  17. 39
  18. No
  19. 53
  20. 131
  21. 39
  22. 53
  23. Yes
  24. 100
  25. 65
  26. 69
  27. 51
  28. 76
  29. No
  30. 68
  31. 87
  32. 58
  33. 89
  34. 68
  35. 112
  36. No
  37. 119
  38. 77
  39. 21
  40. 27

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