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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 700 · 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 = 24° and angle B = 65°. What is angle C (in degrees)?
  2. 2.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  3. 3.In triangle ABC, angle A = 59° and angle B = 25°. What is angle C (in degrees)?
  4. 4.Can a triangle have sides of 17 cm, 7 cm and 7 cm? (a) Yes (b) No
  5. 5.In an isosceles triangle, the two equal angles are 45° each. What is the third angle (in degrees)?
  6. 6.In a right-angled triangle, one of the other two angles is 53°. What is the third angle (in degrees)?
  7. 7.In a right-angled triangle, one of the other two angles is 20°. What is the third angle (in degrees)?
  8. 8.Can a triangle have sides of 12 cm, 17 cm and 4 cm? (a) Yes (b) No
  9. 9.An exterior angle of a triangle is 85°. One of its two interior opposite angles is 20°. What is the other one (in degrees)?
  10. 10.In an isosceles triangle, the two equal angles are 54° each. What is the third angle (in degrees)?
  11. 11.In triangle ABC, angle A = 72° and angle B = 42°. What is angle C (in degrees)?
  12. 12.An exterior angle of a triangle is 113°. One of its two interior opposite angles is 35°. What is the other one (in degrees)?
  13. 13.Can a triangle have sides of 10 cm, 21 cm and 9 cm? (a) Yes (b) No
  14. 14.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)?
  15. 15.An exterior angle of a triangle is 109°. One of its two interior opposite angles is 38°. What is the other one (in degrees)?
  16. 16.The angles of a triangle are in the ratio 3 : 3 : 4. What is the smallest angle (in degrees)?
  17. 17.In triangle ABC, angle A = 67° and angle B = 86°. What is angle C (in degrees)?
  18. 18.In triangle ABC, angle A = 46° and angle B = 43°. What is angle C (in degrees)?
  19. 19.Can a triangle have sides of 5 cm, 7 cm and 12 cm? (a) Yes (b) No
  20. 20.Can a triangle have sides of 3 cm, 11 cm and 4 cm? (a) No (b) Yes
  21. 21.The angles of a triangle are in the ratio 1 : 2 : 6. What is the smallest angle (in degrees)?
  22. 22.An exterior angle of a triangle is 135°. One of its two interior opposite angles is 69°. What is the other one (in degrees)?
  23. 23.In triangle ABC, angle A = 76° and angle B = 75°. What is angle C (in degrees)?
  24. 24.The angles of a triangle are in the ratio 1 : 2 : 3. What is the biggest angle (in degrees)?
  25. 25.In a right-angled triangle, one of the other two angles is 70°. What is the third angle (in degrees)?
  26. 26.The two interior opposite angles of a triangle are 34° and 38°. What is the exterior angle (in degrees)?
  27. 27.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)?
  28. 28.The two interior opposite angles of a triangle are 72° and 49°. What is the exterior angle (in degrees)?
  29. 29.In triangle ABC, angle A = 77° and angle B = 29°. What is angle C (in degrees)?
  30. 30.The two interior opposite angles of a triangle are 29° and 25°. What is the exterior angle (in degrees)?
  31. 31.The two interior opposite angles of a triangle are 30° and 59°. What is the exterior angle (in degrees)?
  32. 32.The two interior opposite angles of a triangle are 70° and 48°. What is the exterior angle (in degrees)?
  33. 33.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  34. 34.Can a triangle have sides of 7 cm, 6 cm and 14 cm? (a) No (b) Yes
  35. 35.An exterior angle of a triangle is 150°. One of its two interior opposite angles is 73°. What is the other one (in degrees)?
  36. 36.An exterior angle of a triangle is 101°. One of its two interior opposite angles is 62°. What is the other one (in degrees)?
  37. 37.The longest side of a right-angled triangle is 5 cm and one of the other sides is 3 cm. How long is the third side (in cm)?
  38. 38.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?
  39. 39.Can a triangle have sides of 25 cm, 12 cm and 9 cm? (a) No (b) Yes
  40. 40.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?

Answer key

  1. 91
  2. 100
  3. 96
  4. No
  5. 90
  6. 37
  7. 70
  8. No
  9. 65
  10. 72
  11. 66
  12. 78
  13. No
  14. 7
  15. 71
  16. 54
  17. 27
  18. 91
  19. No
  20. No
  21. 20
  22. 66
  23. 29
  24. 90
  25. 20
  26. 72
  27. 24
  28. 121
  29. 74
  30. 54
  31. 89
  32. 118
  33. 100
  34. No
  35. 77
  36. 39
  37. 4
  38. 48
  39. No
  40. 90

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