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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 353 · 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 11 cm, 12 cm and 9 cm? (a) No (b) Yes
  2. 2.The longest side of a right-angled triangle is 30 cm and one of the other sides is 18 cm. How long is the third side (in cm)?
  3. 3.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  4. 4.Can a triangle have sides of 12 cm, 15 cm and 9 cm? (a) No (b) Yes
  5. 5.An exterior angle of a triangle is 88°. One of its two interior opposite angles is 38°. What is the other one (in degrees)?
  6. 6.Can a triangle have sides of 9 cm, 17 cm and 4 cm? (a) No (b) Yes
  7. 7.An exterior angle of a triangle is 102°. One of its two interior opposite angles is 22°. What is the other one (in degrees)?
  8. 8.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?
  9. 9.The longest side of a right-angled triangle is 13 cm and one of the other sides is 5 cm. How long is the third side (in cm)?
  10. 10.Can a triangle have sides of 16 cm, 10 cm and 2 cm? (a) Yes (b) No
  11. 11.In an isosceles triangle, the two equal angles are 73° each. What is the third angle (in degrees)?
  12. 12.Can a triangle have sides of 8 cm, 9 cm and 18 cm? (a) No (b) Yes
  13. 13.An exterior angle of a triangle is 114°. One of its two interior opposite angles is 50°. What is the other one (in degrees)?
  14. 14.In an isosceles triangle, the angle between the two equal sides is 72°. What is each of the other two angles (in degrees)?
  15. 15.In a right-angled triangle, one of the other two angles is 75°. What is the third angle (in degrees)?
  16. 16.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  17. 17.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  18. 18.In an isosceles triangle, the angle between the two equal sides is 142°. What is each of the other two angles (in degrees)?
  19. 19.An exterior angle of a triangle is 70°. One of its two interior opposite angles is 32°. What is the other one (in degrees)?
  20. 20.In an isosceles triangle, the angle between the two equal sides is 160°. What is each of the other two angles (in degrees)?
  21. 21.In an isosceles triangle, the angle between the two equal sides is 60°. What is each of the other two angles (in degrees)?
  22. 22.In triangle ABC, angle A = 88° and angle B = 23°. What is angle C (in degrees)?
  23. 23.In an isosceles triangle, the angle between the two equal sides is 54°. What is each of the other two angles (in degrees)?
  24. 24.Can a triangle have sides of 12 cm, 3 cm and 8 cm? (a) No (b) Yes
  25. 25.In triangle ABC, angle A = 70° and angle B = 37°. What is angle C (in degrees)?
  26. 26.In triangle ABC, angle A = 56° and angle B = 58°. What is angle C (in degrees)?
  27. 27.In triangle ABC, angle A = 49° and angle B = 45°. What is angle C (in degrees)?
  28. 28.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  29. 29.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  30. 30.The two shorter sides of a right-angled triangle are 24 cm and 18 cm. How long is the longest side (in cm)?
  31. 31.The angles of a triangle are in the ratio 1 : 2 : 2. What is the smallest angle (in degrees)?
  32. 32.Can a triangle have sides of 12 cm, 2 cm and 15 cm? (a) Yes (b) No
  33. 33.An exterior angle of a triangle is 88°. One of its two interior opposite angles is 20°. What is the other one (in degrees)?
  34. 34.In triangle ABC, angle A = 48° and angle B = 71°. What is angle C (in degrees)?
  35. 35.In an isosceles triangle, the two equal angles are 85° each. What is the third angle (in degrees)?
  36. 36.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?
  37. 37.Can a triangle have sides of 6 cm, 12 cm and 5 cm? (a) Yes (b) No
  38. 38.In an isosceles triangle, the two equal angles are 70° each. What is the third angle (in degrees)?
  39. 39.In triangle ABC, angle A = 47° and angle B = 50°. What is angle C (in degrees)?
  40. 40.In an isosceles triangle, the angle between the two equal sides is 36°. What is each of the other two angles (in degrees)?

Answer key

  1. Yes
  2. 24
  3. 72
  4. Yes
  5. 50
  6. No
  7. 80
  8. 48
  9. 12
  10. No
  11. 34
  12. No
  13. 64
  14. 54
  15. 15
  16. 25
  17. 100
  18. 19
  19. 38
  20. 10
  21. 60
  22. 69
  23. 63
  24. No
  25. 73
  26. 66
  27. 86
  28. 17
  29. 40
  30. 30
  31. 36
  32. No
  33. 68
  34. 61
  35. 10
  36. 50
  37. No
  38. 40
  39. 83
  40. 72

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