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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 332 · 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 = 95° and angle B = 53°. What is angle C (in degrees)?
  2. 2.In an isosceles triangle, the angle between the two equal sides is 72°. What is each of the other two angles (in degrees)?
  3. 3.In a right-angled triangle, one of the other two angles is 48°. What is the third angle (in degrees)?
  4. 4.The two interior opposite angles of a triangle are 76° and 65°. What is the exterior angle (in degrees)?
  5. 5.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  6. 6.In triangle ABC, angle A = 38° and angle B = 32°. What is angle C (in degrees)?
  7. 7.In a right-angled triangle, one of the other two angles is 63°. What is the third angle (in degrees)?
  8. 8.Can a triangle have sides of 24 cm, 9 cm and 11 cm? (a) No (b) Yes
  9. 9.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  10. 10.In triangle ABC, angle A = 47° and angle B = 101°. What is angle C (in degrees)?
  11. 11.In a right-angled triangle, one of the other two angles is 74°. What is the third angle (in degrees)?
  12. 12.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  13. 13.Can a triangle have sides of 10 cm, 3 cm and 8 cm? (a) Yes (b) No
  14. 14.In triangle ABC, angle A = 25° and angle B = 36°. What is angle C (in degrees)?
  15. 15.Can a triangle have sides of 14 cm, 4 cm and 12 cm? (a) No (b) Yes
  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 interior opposite angles of a triangle are 55° and 32°. What is the exterior angle (in degrees)?
  18. 18.Can a triangle have sides of 9 cm, 9 cm and 23 cm? (a) Yes (b) No
  19. 19.The angles of a triangle are in the ratio 5 : 6 : 7. What is the biggest angle (in degrees)?
  20. 20.In triangle ABC, angle A = 75° and angle B = 46°. What is angle C (in degrees)?
  21. 21.Can a triangle have sides of 2 cm, 7 cm and 6 cm? (a) No (b) Yes
  22. 22.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)?
  23. 23.In a right-angled triangle, one of the other two angles is 80°. What is the third angle (in degrees)?
  24. 24.An exterior angle of a triangle is 97°. One of its two interior opposite angles is 20°. What is the other one (in degrees)?
  25. 25.In a right-angled triangle, one of the other two angles is 21°. What is the third angle (in degrees)?
  26. 26.In a right-angled triangle, one of the other two angles is 30°. What is the third angle (in degrees)?
  27. 27.The two shorter sides of a right-angled triangle are 10 cm and 24 cm. How long is the longest side (in cm)?
  28. 28.Can a triangle have sides of 8 cm, 11 cm and 7 cm? (a) Yes (b) No
  29. 29.In triangle ABC, angle A = 94° and angle B = 60°. What is angle C (in degrees)?
  30. 30.Can a triangle have sides of 16 cm, 7 cm and 4 cm? (a) Yes (b) No
  31. 31.Can a triangle have sides of 9 cm, 2 cm and 7 cm? (a) Yes (b) No
  32. 32.In triangle ABC, angle A = 100° and angle B = 30°. What is angle C (in degrees)?
  33. 33.An exterior angle of a triangle is 91°. One of its two interior opposite angles is 33°. What is the other one (in degrees)?
  34. 34.An exterior angle of a triangle is 107°. One of its two interior opposite angles is 72°. What is the other one (in degrees)?
  35. 35.In triangle ABC, angle A = 70° and angle B = 40°. What is angle C (in degrees)?
  36. 36.In triangle ABC, angle A = 31° and angle B = 24°. What is angle C (in degrees)?
  37. 37.In an isosceles triangle, the two equal angles are 75° each. What is the third angle (in degrees)?
  38. 38.Can a triangle have sides of 18 cm, 8 cm and 10 cm? (a) No (b) Yes
  39. 39.In an isosceles triangle, the angle between the two equal sides is 62°. What is each of the other two angles (in degrees)?
  40. 40.The two shorter sides of a right-angled triangle are 20 cm and 15 cm. How long is the longest side (in cm)?

Answer key

  1. 32
  2. 54
  3. 42
  4. 141
  5. 25
  6. 110
  7. 27
  8. No
  9. 17
  10. 32
  11. 16
  12. 90
  13. Yes
  14. 119
  15. Yes
  16. 3
  17. 87
  18. No
  19. 70
  20. 59
  21. Yes
  22. 24
  23. 10
  24. 77
  25. 69
  26. 60
  27. 26
  28. Yes
  29. 26
  30. No
  31. No
  32. 50
  33. 58
  34. 35
  35. 70
  36. 125
  37. 30
  38. No
  39. 59
  40. 25

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