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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 298 · 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.

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  1. 1.In a right-angled triangle, one of the other two angles is 30°. What is the third angle (in degrees)?
  2. 2.Can a triangle have sides of 17 cm, 5 cm and 9 cm? (a) Yes (b) No
  3. 3.In triangle ABC, angle A = 90° and angle B = 21°. What is angle C (in degrees)?
  4. 4.In triangle ABC, angle A = 54° and angle B = 43°. What is angle C (in degrees)?
  5. 5.In a right-angled triangle, one of the other two angles is 11°. What is the third angle (in degrees)?
  6. 6.In an isosceles triangle, the angle between the two equal sides is 102°. What is each of the other two angles (in degrees)?
  7. 7.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  8. 8.The two interior opposite angles of a triangle are 46° and 32°. What is the exterior angle (in degrees)?
  9. 9.An exterior angle of a triangle is 90°. One of its two interior opposite angles is 66°. What is the other one (in degrees)?
  10. 10.In an isosceles triangle, the two equal angles are 36° each. What is the third angle (in degrees)?
  11. 11.The two shorter sides of a right-angled triangle are 24 cm and 10 cm. How long is the longest side (in cm)?
  12. 12.Can a triangle have sides of 10 cm, 2 cm and 7 cm? (a) Yes (b) No
  13. 13.Can a triangle have sides of 17 cm, 10 cm and 5 cm? (a) No (b) Yes
  14. 14.In an isosceles triangle, the two equal angles are 47° each. What is the third angle (in degrees)?
  15. 15.In triangle ABC, angle A = 50° and angle B = 87°. What is angle C (in degrees)?
  16. 16.In a right-angled triangle, one of the other two angles is 54°. What is the third angle (in degrees)?
  17. 17.The two shorter sides of a right-angled triangle are 36 cm and 15 cm. How long is the longest side (in cm)?
  18. 18.The longest side of a right-angled triangle is 15 cm and one of the other sides is 12 cm. How long is the third side (in cm)?
  19. 19.The angles of a triangle are in the ratio 1 : 2 : 2. What is the biggest angle (in degrees)?
  20. 20.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)?
  21. 21.In a right-angled triangle, one of the other two angles is 17°. What is the third angle (in degrees)?
  22. 22.In a right-angled triangle, one of the other two angles is 46°. What is the third angle (in degrees)?
  23. 23.An exterior angle of a triangle is 121°. One of its two interior opposite angles is 68°. What is the other one (in degrees)?
  24. 24.In triangle ABC, angle A = 31° and angle B = 26°. What is angle C (in degrees)?
  25. 25.The two shorter sides of a right-angled triangle are 18 cm and 24 cm. How long is the longest side (in cm)?
  26. 26.In triangle ABC, angle A = 89° and angle B = 57°. What is angle C (in degrees)?
  27. 27.Can a triangle have sides of 14 cm, 6 cm and 12 cm? (a) Yes (b) No
  28. 28.In triangle ABC, angle A = 66° and angle B = 31°. What is angle C (in degrees)?
  29. 29.The two interior opposite angles of a triangle are 24° and 56°. What is the exterior angle (in degrees)?
  30. 30.The angles of a triangle are in the ratio 3 : 5 : 7. What is the biggest angle (in degrees)?
  31. 31.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  32. 32.The longest side of a right-angled triangle is 25 cm and one of the other sides is 7 cm. How long is the third side (in cm)?
  33. 33.In triangle ABC, angle A = 39° and angle B = 20°. What is angle C (in degrees)?
  34. 34.In an isosceles triangle, the angle between the two equal sides is 144°. What is each of the other two angles (in degrees)?
  35. 35.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  36. 36.In triangle ABC, angle A = 36° and angle B = 67°. What is angle C (in degrees)?
  37. 37.The longest side of a right-angled triangle is 30 cm and one of the other sides is 24 cm. How long is the third side (in cm)?
  38. 38.In a right-angled triangle, one of the other two angles is 62°. What is the third angle (in degrees)?
  39. 39.Can a triangle have sides of 13 cm, 11 cm and 3 cm? (a) No (b) Yes
  40. 40.The longest side of a right-angled triangle is 26 cm and one of the other sides is 24 cm. How long is the third side (in cm)?

Answer key

  1. 60
  2. No
  3. 69
  4. 83
  5. 79
  6. 39
  7. 100
  8. 78
  9. 24
  10. 108
  11. 26
  12. No
  13. No
  14. 86
  15. 43
  16. 36
  17. 39
  18. 9
  19. 72
  20. 12
  21. 73
  22. 44
  23. 53
  24. 123
  25. 30
  26. 34
  27. Yes
  28. 83
  29. 80
  30. 84
  31. 72
  32. 24
  33. 121
  34. 18
  35. 17
  36. 77
  37. 18
  38. 28
  39. Yes
  40. 10

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