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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 579 · 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 7 cm, 8 cm and 12 cm? (a) No (b) Yes
  2. 2.In triangle ABC, angle A = 23° and angle B = 73°. What is angle C (in degrees)?
  3. 3.In a right-angled triangle, one of the other two angles is 56°. What is the third angle (in degrees)?
  4. 4.Can a triangle have sides of 9 cm, 24 cm and 11 cm? (a) No (b) Yes
  5. 5.In an isosceles triangle, the angle between the two equal sides is 50°. What is each of the other two angles (in degrees)?
  6. 6.An exterior angle of a triangle is 116°. One of its two interior opposite angles is 42°. What is the other one (in degrees)?
  7. 7.Can a triangle have sides of 6 cm, 3 cm and 5 cm? (a) Yes (b) No
  8. 8.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  9. 9.The two interior opposite angles of a triangle are 48° and 24°. What is the exterior angle (in degrees)?
  10. 10.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)?
  11. 11.Can a triangle have sides of 5 cm, 12 cm and 19 cm? (a) Yes (b) No
  12. 12.In an isosceles triangle, the angle between the two equal sides is 24°. What is each of the other two angles (in degrees)?
  13. 13.In a right-angled triangle, one of the other two angles is 10°. What is the third angle (in degrees)?
  14. 14.In an isosceles triangle, the angle between the two equal sides is 80°. What is each of the other two angles (in degrees)?
  15. 15.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  16. 16.The longest side of a right-angled triangle is 5 cm and one of the other sides is 4 cm. How long is the third side (in cm)?
  17. 17.The two shorter sides of a right-angled triangle are 5 cm and 12 cm. How long is the longest side (in cm)?
  18. 18.The two shorter sides of a right-angled triangle are 10 cm and 24 cm. How long is the longest side (in cm)?
  19. 19.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  20. 20.In an isosceles triangle, the angle between the two equal sides is 62°. What is each of the other two angles (in degrees)?
  21. 21.Can a triangle have sides of 22 cm, 10 cm and 9 cm? (a) Yes (b) No
  22. 22.In an isosceles triangle, the angle between the two equal sides is 84°. What is each of the other two angles (in degrees)?
  23. 23.In an isosceles triangle, the angle between the two equal sides is 46°. What is each of the other two angles (in degrees)?
  24. 24.In triangle ABC, angle A = 39° and angle B = 76°. What is angle C (in degrees)?
  25. 25.The longest side of a right-angled triangle is 13 cm and one of the other sides is 12 cm. How long is the third side (in cm)?
  26. 26.An exterior angle of a triangle is 67°. One of its two interior opposite angles is 35°. What is the other one (in degrees)?
  27. 27.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?
  28. 28.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)?
  29. 29.In an isosceles triangle, the two equal angles are 58° each. What is the third angle (in degrees)?
  30. 30.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  31. 31.Can a triangle have sides of 8 cm, 3 cm and 16 cm? (a) No (b) Yes
  32. 32.In a right-angled triangle, one of the other two angles is 13°. What is the third angle (in degrees)?
  33. 33.In a right-angled triangle, one of the other two angles is 40°. What is the third angle (in degrees)?
  34. 34.In a right-angled triangle, one of the other two angles is 36°. What is the third angle (in degrees)?
  35. 35.In an isosceles triangle, the angle between the two equal sides is 86°. What is each of the other two angles (in degrees)?
  36. 36.In triangle ABC, angle A = 88° and angle B = 30°. What is angle C (in degrees)?
  37. 37.The angles of a triangle are in the ratio 1 : 2 : 2. What is the biggest angle (in degrees)?
  38. 38.In triangle ABC, angle A = 36° and angle B = 71°. What is angle C (in degrees)?
  39. 39.The longest side of a right-angled triangle is 17 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  40. 40.In a right-angled triangle, one of the other two angles is 15°. What is the third angle (in degrees)?

Answer key

  1. Yes
  2. 84
  3. 34
  4. No
  5. 65
  6. 74
  7. Yes
  8. 25
  9. 72
  10. 8
  11. No
  12. 78
  13. 80
  14. 50
  15. 100
  16. 3
  17. 13
  18. 26
  19. 25
  20. 59
  21. No
  22. 48
  23. 67
  24. 65
  25. 5
  26. 32
  27. 48
  28. 15
  29. 64
  30. 90
  31. No
  32. 77
  33. 50
  34. 54
  35. 47
  36. 62
  37. 72
  38. 73
  39. 8
  40. 75

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