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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 499 · 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 22°. What is the third angle (in degrees)?
  2. 2.In triangle ABC, angle A = 38° and angle B = 116°. What is angle C (in degrees)?
  3. 3.The two shorter sides of a right-angled triangle are 36 cm and 15 cm. How long is the longest side (in cm)?
  4. 4.In triangle ABC, angle A = 94° and angle B = 35°. What is angle C (in degrees)?
  5. 5.The two interior opposite angles of a triangle are 54° and 80°. What is the exterior angle (in degrees)?
  6. 6.Can a triangle have sides of 16 cm, 4 cm and 9 cm? (a) No (b) Yes
  7. 7.Can a triangle have sides of 3 cm, 6 cm and 4 cm? (a) No (b) Yes
  8. 8.In a right-angled triangle, one of the other two angles is 53°. What is the third angle (in degrees)?
  9. 9.The two interior opposite angles of a triangle are 24° and 58°. What is the exterior angle (in degrees)?
  10. 10.An exterior angle of a triangle is 90°. One of its two interior opposite angles is 29°. What is the other one (in degrees)?
  11. 11.Can a triangle have sides of 11 cm, 24 cm and 9 cm? (a) No (b) Yes
  12. 12.In a right-angled triangle, one of the other two angles is 28°. What is the third angle (in degrees)?
  13. 13.An exterior angle of a triangle is 91°. One of its two interior opposite angles is 47°. What is the other one (in degrees)?
  14. 14.Can a triangle have sides of 14 cm, 6 cm and 5 cm? (a) No (b) Yes
  15. 15.In a right-angled triangle, one of the other two angles is 27°. What is the third angle (in degrees)?
  16. 16.An exterior angle of a triangle is 102°. One of its two interior opposite angles is 30°. What is the other one (in degrees)?
  17. 17.In an isosceles triangle, the angle between the two equal sides is 58°. What is each of the other two angles (in degrees)?
  18. 18.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  19. 19.Can a triangle have sides of 10 cm, 3 cm and 15 cm? (a) Yes (b) No
  20. 20.An exterior angle of a triangle is 85°. One of its two interior opposite angles is 38°. What is the other one (in degrees)?
  21. 21.In an isosceles triangle, the angle between the two equal sides is 88°. What is each of the other two angles (in degrees)?
  22. 22.In a right-angled triangle, one of the other two angles is 80°. What is the third angle (in degrees)?
  23. 23.In an isosceles triangle, the angle between the two equal sides is 106°. What is each of the other two angles (in degrees)?
  24. 24.The angles of a triangle are in the ratio 2 : 3 : 5. What is the smallest angle (in degrees)?
  25. 25.In an isosceles triangle, the angle between the two equal sides is 52°. What is each of the other two angles (in degrees)?
  26. 26.An exterior angle of a triangle is 59°. One of its two interior opposite angles is 31°. What is the other one (in degrees)?
  27. 27.The angles of a triangle are in the ratio 3 : 5 : 7. What is the biggest angle (in degrees)?
  28. 28.An exterior angle of a triangle is 93°. One of its two interior opposite angles is 62°. What is the other one (in degrees)?
  29. 29.In triangle ABC, angle A = 42° and angle B = 63°. What is angle C (in degrees)?
  30. 30.In triangle ABC, angle A = 60° and angle B = 57°. What is angle C (in degrees)?
  31. 31.In an isosceles triangle, the angle between the two equal sides is 118°. What is each of the other two angles (in degrees)?
  32. 32.In triangle ABC, angle A = 42° and angle B = 50°. What is angle C (in degrees)?
  33. 33.Can a triangle have sides of 11 cm, 7 cm and 9 cm? (a) No (b) Yes
  34. 34.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)?
  35. 35.In an isosceles triangle, the angle between the two equal sides is 138°. What is each of the other two angles (in degrees)?
  36. 36.The two interior opposite angles of a triangle are 37° and 32°. What is the exterior angle (in degrees)?
  37. 37.In triangle ABC, angle A = 72° and angle B = 47°. What is angle C (in degrees)?
  38. 38.An exterior angle of a triangle is 67°. One of its two interior opposite angles is 31°. What is the other one (in degrees)?
  39. 39.In an isosceles triangle, the angle between the two equal sides is 150°. What is each of the other two angles (in degrees)?
  40. 40.Can a triangle have sides of 9 cm, 9 cm and 6 cm? (a) No (b) Yes

Answer key

  1. 68
  2. 26
  3. 39
  4. 51
  5. 134
  6. No
  7. Yes
  8. 37
  9. 82
  10. 61
  11. No
  12. 62
  13. 44
  14. No
  15. 63
  16. 72
  17. 61
  18. 18
  19. No
  20. 47
  21. 46
  22. 10
  23. 37
  24. 36
  25. 64
  26. 28
  27. 84
  28. 31
  29. 75
  30. 63
  31. 31
  32. 88
  33. Yes
  34. 9
  35. 21
  36. 69
  37. 61
  38. 36
  39. 15
  40. Yes

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