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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 518 · 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 19 cm, 8 cm and 6 cm? (a) Yes (b) No
  2. 2.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  3. 3.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  4. 4.In an isosceles triangle, the two equal angles are 37° each. What is the third angle (in degrees)?
  5. 5.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (in degrees)?
  6. 6.In triangle ABC, angle A = 31° and angle B = 26°. What is angle C (in degrees)?
  7. 7.An exterior angle of a triangle is 74°. One of its two interior opposite angles is 31°. What is the other one (in degrees)?
  8. 8.Can a triangle have sides of 11 cm, 15 cm and 6 cm? (a) No (b) Yes
  9. 9.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)?
  10. 10.In an isosceles triangle, the angle between the two equal sides is 74°. What is each of the other two angles (in degrees)?
  11. 11.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  12. 12.The angles of a triangle are in the ratio 3 : 3 : 4. What is the smallest angle (in degrees)?
  13. 13.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  14. 14.An exterior angle of a triangle is 99°. One of its two interior opposite angles is 56°. What is the other one (in degrees)?
  15. 15.Can a triangle have sides of 5 cm, 5 cm and 15 cm? (a) Yes (b) No
  16. 16.Can a triangle have sides of 7 cm, 2 cm and 5 cm? (a) No (b) Yes
  17. 17.In an isosceles triangle, the two equal angles are 25° each. What is the third angle (in degrees)?
  18. 18.In an isosceles triangle, the two equal angles are 69° each. What is the third angle (in degrees)?
  19. 19.In an isosceles triangle, the angle between the two equal sides is 128°. What is each of the other two angles (in degrees)?
  20. 20.The longest side of a right-angled triangle is 10 cm and one of the other sides is 8 cm. How long is the third side (in cm)?
  21. 21.In a right-angled triangle, one of the other two angles is 66°. What is the third angle (in degrees)?
  22. 22.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  23. 23.Can a triangle have sides of 8 cm, 6 cm and 16 cm? (a) No (b) Yes
  24. 24.The longest side of a right-angled triangle is 39 cm and one of the other sides is 36 cm. How long is the third side (in cm)?
  25. 25.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  26. 26.In triangle ABC, angle A = 92° and angle B = 24°. What is angle C (in degrees)?
  27. 27.Can a triangle have sides of 6 cm, 4 cm and 11 cm? (a) Yes (b) No
  28. 28.In an isosceles triangle, the angle between the two equal sides is 134°. What is each of the other two angles (in degrees)?
  29. 29.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)?
  30. 30.In a right-angled triangle, one of the other two angles is 51°. What is the third angle (in degrees)?
  31. 31.In triangle ABC, angle A = 20° and angle B = 31°. What is angle C (in degrees)?
  32. 32.In triangle ABC, angle A = 25° and angle B = 35°. What is angle C (in degrees)?
  33. 33.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  34. 34.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  35. 35.The two interior opposite angles of a triangle are 27° and 60°. What is the exterior angle (in degrees)?
  36. 36.Can a triangle have sides of 10 cm, 10 cm and 21 cm? (a) Yes (b) No
  37. 37.In an isosceles triangle, the two equal angles are 60° each. What is the third angle (in degrees)?
  38. 38.Can a triangle have sides of 13 cm, 2 cm and 10 cm? (a) Yes (b) No
  39. 39.In an isosceles triangle, the two equal angles are 54° each. What is the third angle (in degrees)?
  40. 40.An exterior angle of a triangle is 95°. One of its two interior opposite angles is 58°. What is the other one (in degrees)?

Answer key

  1. No
  2. 90
  3. 80
  4. 106
  5. 72
  6. 123
  7. 43
  8. Yes
  9. 15
  10. 53
  11. 17
  12. 54
  13. 100
  14. 43
  15. No
  16. No
  17. 130
  18. 42
  19. 26
  20. 6
  21. 24
  22. 90
  23. No
  24. 15
  25. 25
  26. 64
  27. No
  28. 23
  29. 15
  30. 39
  31. 129
  32. 120
  33. 20
  34. 120
  35. 87
  36. No
  37. 60
  38. No
  39. 72
  40. 37

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