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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 248 · 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 triangle ABC, angle A = 50° and angle B = 53°. What is angle C (in degrees)?
  2. 2.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)?
  3. 3.An exterior angle of a triangle is 131°. One of its two interior opposite angles is 60°. What is the other one (in degrees)?
  4. 4.In triangle ABC, angle A = 58° and angle B = 89°. What is angle C (in degrees)?
  5. 5.In a right-angled triangle, one of the other two angles is 53°. What is the third angle (in degrees)?
  6. 6.Can a triangle have sides of 12 cm, 10 cm and 22 cm? (a) No (b) Yes
  7. 7.The angles of a triangle are in the ratio 5 : 6 : 7. What is the biggest angle (in degrees)?
  8. 8.In an isosceles triangle, the angle between the two equal sides is 20°. What is each of the other two angles (in degrees)?
  9. 9.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  10. 10.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  11. 11.In triangle ABC, angle A = 33° and angle B = 120°. What is angle C (in degrees)?
  12. 12.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)?
  13. 13.In a right-angled triangle, one of the other two angles is 17°. What is the third angle (in degrees)?
  14. 14.In an isosceles triangle, the angle between the two equal sides is 98°. What is each of the other two angles (in degrees)?
  15. 15.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  16. 16.The two shorter sides of a right-angled triangle are 10 cm and 24 cm. How long is the longest side (in cm)?
  17. 17.Can a triangle have sides of 9 cm, 2 cm and 2 cm? (a) Yes (b) No
  18. 18.In an isosceles triangle, the two equal angles are 84° each. What is the third angle (in degrees)?
  19. 19.An exterior angle of a triangle is 96°. One of its two interior opposite angles is 46°. What is the other one (in degrees)?
  20. 20.In a right-angled triangle, one of the other two angles is 45°. What is the third angle (in degrees)?
  21. 21.In triangle ABC, angle A = 46° and angle B = 28°. What is angle C (in degrees)?
  22. 22.An exterior angle of a triangle is 79°. One of its two interior opposite angles is 49°. What is the other one (in degrees)?
  23. 23.Can a triangle have sides of 18 cm, 6 cm and 12 cm? (a) No (b) Yes
  24. 24.An exterior angle of a triangle is 68°. One of its two interior opposite angles is 30°. What is the other one (in degrees)?
  25. 25.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)?
  26. 26.Can a triangle have sides of 10 cm, 19 cm and 6 cm? (a) Yes (b) No
  27. 27.In triangle ABC, angle A = 55° and angle B = 23°. What is angle C (in degrees)?
  28. 28.In an isosceles triangle, the two equal angles are 20° each. What is the third angle (in degrees)?
  29. 29.In triangle ABC, angle A = 32° and angle B = 102°. What is angle C (in degrees)?
  30. 30.Can a triangle have sides of 11 cm, 3 cm and 14 cm? (a) Yes (b) No
  31. 31.Can a triangle have sides of 6 cm, 5 cm and 4 cm? (a) No (b) Yes
  32. 32.An exterior angle of a triangle is 151°. One of its two interior opposite angles is 74°. What is the other one (in degrees)?
  33. 33.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  34. 34.An exterior angle of a triangle is 100°. One of its two interior opposite angles is 72°. What is the other one (in degrees)?
  35. 35.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  36. 36.The two interior opposite angles of a triangle are 72° and 38°. What is the exterior angle (in degrees)?
  37. 37.Can a triangle have sides of 11 cm, 8 cm and 24 cm? (a) No (b) Yes
  38. 38.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  39. 39.Can a triangle have sides of 2 cm, 10 cm and 9 cm? (a) Yes (b) No
  40. 40.The two shorter sides of a right-angled triangle are 16 cm and 12 cm. How long is the longest side (in cm)?

Answer key

  1. 77
  2. 3
  3. 71
  4. 33
  5. 37
  6. No
  7. 70
  8. 80
  9. 18
  10. 17
  11. 27
  12. 24
  13. 73
  14. 41
  15. 25
  16. 26
  17. No
  18. 12
  19. 50
  20. 45
  21. 106
  22. 30
  23. No
  24. 38
  25. 15
  26. No
  27. 102
  28. 140
  29. 46
  30. No
  31. Yes
  32. 77
  33. 90
  34. 28
  35. 20
  36. 110
  37. No
  38. 120
  39. Yes
  40. 20

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