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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 589 · 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 16 cm, 10 cm and 10 cm? (a) No (b) Yes
  2. 2.An exterior angle of a triangle is 89°. One of its two interior opposite angles is 44°. What is the other one (in degrees)?
  3. 3.In an isosceles triangle, the two equal angles are 58° each. What is the third angle (in degrees)?
  4. 4.In an isosceles triangle, the angle between the two equal sides is 98°. What is each of the other two angles (in degrees)?
  5. 5.Can a triangle have sides of 8 cm, 22 cm and 9 cm? (a) Yes (b) No
  6. 6.In an isosceles triangle, the angle between the two equal sides is 86°. What is each of the other two angles (in degrees)?
  7. 7.The two interior opposite angles of a triangle are 27° and 52°. What is the exterior angle (in degrees)?
  8. 8.In a right-angled triangle, one of the other two angles is 12°. What is the third angle (in degrees)?
  9. 9.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)?
  10. 10.The two shorter sides of a right-angled triangle are 18 cm and 24 cm. How long is the longest side (in cm)?
  11. 11.Can a triangle have sides of 7 cm, 15 cm and 11 cm? (a) No (b) Yes
  12. 12.In an isosceles triangle, the angle between the two equal sides is 28°. What is each of the other two angles (in degrees)?
  13. 13.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  14. 14.An exterior angle of a triangle is 104°. One of its two interior opposite angles is 53°. What is the other one (in degrees)?
  15. 15.Can a triangle have sides of 2 cm, 5 cm and 5 cm? (a) Yes (b) No
  16. 16.The two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  17. 17.The two interior opposite angles of a triangle are 64° and 32°. What is the exterior angle (in degrees)?
  18. 18.The longest side of a right-angled triangle is 17 cm and one of the other sides is 8 cm. How long is the third side (in cm)?
  19. 19.Can a triangle have sides of 7 cm, 12 cm and 10 cm? (a) Yes (b) No
  20. 20.In triangle ABC, angle A = 66° and angle B = 47°. What is angle C (in degrees)?
  21. 21.In triangle ABC, angle A = 55° and angle B = 93°. What is angle C (in degrees)?
  22. 22.The two shorter sides of a right-angled triangle are 36 cm and 15 cm. How long is the longest side (in cm)?
  23. 23.In an isosceles triangle, the angle between the two equal sides is 64°. What is each of the other two angles (in degrees)?
  24. 24.In triangle ABC, angle A = 30° and angle B = 43°. What is angle C (in degrees)?
  25. 25.In triangle ABC, angle A = 26° and angle B = 44°. What is angle C (in degrees)?
  26. 26.An exterior angle of a triangle is 55°. One of its two interior opposite angles is 35°. What is the other one (in degrees)?
  27. 27.Can a triangle have sides of 10 cm, 3 cm and 17 cm? (a) Yes (b) No
  28. 28.In an isosceles triangle, the angle between the two equal sides is 150°. What is each of the other two angles (in degrees)?
  29. 29.In an isosceles triangle, the angle between the two equal sides is 24°. What is each of the other two angles (in degrees)?
  30. 30.In a right-angled triangle, one of the other two angles is 80°. What is the third angle (in degrees)?
  31. 31.The angles of a triangle are in the ratio 3 : 5 : 7. What is the biggest angle (in degrees)?
  32. 32.Can a triangle have sides of 17 cm, 5 cm and 11 cm? (a) No (b) Yes
  33. 33.In triangle ABC, angle A = 65° and angle B = 35°. What is angle C (in degrees)?
  34. 34.Can a triangle have sides of 26 cm, 11 cm and 10 cm? (a) Yes (b) No
  35. 35.An exterior angle of a triangle is 108°. One of its two interior opposite angles is 72°. What is the other one (in degrees)?
  36. 36.The two interior opposite angles of a triangle are 76° and 33°. What is the exterior angle (in degrees)?
  37. 37.An exterior angle of a triangle is 111°. One of its two interior opposite angles is 77°. What is the other one (in degrees)?
  38. 38.In triangle ABC, angle A = 33° and angle B = 30°. What is angle C (in degrees)?
  39. 39.In triangle ABC, angle A = 33° and angle B = 85°. What is angle C (in degrees)?
  40. 40.In triangle ABC, angle A = 88° and angle B = 65°. What is angle C (in degrees)?

Answer key

  1. Yes
  2. 45
  3. 64
  4. 41
  5. No
  6. 47
  7. 79
  8. 78
  9. 8
  10. 30
  11. Yes
  12. 76
  13. 18
  14. 51
  15. Yes
  16. 39
  17. 96
  18. 15
  19. Yes
  20. 67
  21. 32
  22. 39
  23. 58
  24. 107
  25. 110
  26. 20
  27. No
  28. 15
  29. 78
  30. 10
  31. 84
  32. No
  33. 80
  34. No
  35. 36
  36. 109
  37. 34
  38. 117
  39. 62
  40. 27

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