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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 587 · 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.Can a triangle have sides of 10 cm, 10 cm and 22 cm? (a) No (b) Yes
  2. 2.In triangle ABC, angle A = 38° and angle B = 105°. What is angle C (in degrees)?
  3. 3.The two interior opposite angles of a triangle are 48° and 37°. What is the exterior angle (in degrees)?
  4. 4.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  5. 5.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  6. 6.The two shorter sides of a right-angled triangle are 10 cm and 24 cm. How long is the longest side (in cm)?
  7. 7.The two interior opposite angles of a triangle are 72° and 34°. What is the exterior angle (in degrees)?
  8. 8.In an isosceles triangle, the angle between the two equal sides is 58°. What is each of the other two angles (in degrees)?
  9. 9.The longest side of a right-angled triangle is 25 cm and one of the other sides is 24 cm. How long is the third side (in cm)?
  10. 10.The two interior opposite angles of a triangle are 66° and 45°. What is the exterior angle (in degrees)?
  11. 11.The two interior opposite angles of a triangle are 37° and 55°. What is the exterior 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.The two interior opposite angles of a triangle are 63° and 43°. What is the exterior angle (in degrees)?
  14. 14.In triangle ABC, angle A = 83° and angle B = 67°. What is angle C (in degrees)?
  15. 15.The angles of a triangle are in the ratio 1 : 2 : 3. What is the biggest angle (in degrees)?
  16. 16.In a right-angled triangle, one of the other two angles is 18°. What is the third angle (in degrees)?
  17. 17.Can a triangle have sides of 9 cm, 6 cm and 20 cm? (a) Yes (b) No
  18. 18.An exterior angle of a triangle is 107°. One of its two interior opposite angles is 66°. What is the other one (in degrees)?
  19. 19.In triangle ABC, angle A = 29° and angle B = 29°. What is angle C (in degrees)?
  20. 20.In triangle ABC, angle A = 72° and angle B = 22°. What is angle C (in degrees)?
  21. 21.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  22. 22.An exterior angle of a triangle is 121°. One of its two interior opposite angles is 55°. What is the other one (in degrees)?
  23. 23.In triangle ABC, angle A = 85° and angle B = 36°. What is angle C (in degrees)?
  24. 24.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?
  25. 25.In a right-angled triangle, one of the other two angles is 61°. What is the third angle (in degrees)?
  26. 26.In an isosceles triangle, the two equal angles are 46° each. What is the third angle (in degrees)?
  27. 27.In triangle ABC, angle A = 41° and angle B = 101°. What is angle C (in degrees)?
  28. 28.An exterior angle of a triangle is 96°. One of its two interior opposite angles is 61°. What is the other one (in degrees)?
  29. 29.The two interior opposite angles of a triangle are 29° and 65°. What is the exterior angle (in degrees)?
  30. 30.Can a triangle have sides of 24 cm, 11 cm and 10 cm? (a) Yes (b) No
  31. 31.In a right-angled triangle, one of the other two angles is 29°. What is the third angle (in degrees)?
  32. 32.The two interior opposite angles of a triangle are 76° and 27°. What is the exterior angle (in degrees)?
  33. 33.In a right-angled triangle, one of the other two angles is 45°. What is the third angle (in degrees)?
  34. 34.In triangle ABC, angle A = 63° and angle B = 85°. What is angle C (in degrees)?
  35. 35.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  36. 36.An exterior angle of a triangle is 101°. One of its two interior opposite angles is 21°. What is the other one (in degrees)?
  37. 37.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  38. 38.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)?
  39. 39.In triangle ABC, angle A = 48° and angle B = 47°. What is angle C (in degrees)?
  40. 40.Can a triangle have sides of 11 cm, 17 cm and 5 cm? (a) No (b) Yes

Answer key

  1. No
  2. 37
  3. 85
  4. 90
  5. 17
  6. 26
  7. 106
  8. 61
  9. 7
  10. 111
  11. 92
  12. 90
  13. 106
  14. 30
  15. 90
  16. 72
  17. No
  18. 41
  19. 122
  20. 86
  21. 45
  22. 66
  23. 59
  24. 50
  25. 29
  26. 88
  27. 38
  28. 35
  29. 94
  30. No
  31. 61
  32. 103
  33. 45
  34. 32
  35. 17
  36. 80
  37. 100
  38. 8
  39. 85
  40. No

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