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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 942 · 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 = 56° and angle B = 60°. What is angle C (in degrees)?
  2. 2.The two interior opposite angles of a triangle are 46° and 42°. What is the exterior angle (in degrees)?
  3. 3.Can a triangle have sides of 8 cm, 4 cm and 7 cm? (a) No (b) Yes
  4. 4.The two interior opposite angles of a triangle are 52° and 47°. What is the exterior angle (in degrees)?
  5. 5.In an isosceles triangle, the angle between the two equal sides is 32°. What is each of the other two angles (in degrees)?
  6. 6.In a right-angled triangle, one of the other two angles is 69°. What is the third angle (in degrees)?
  7. 7.An exterior angle of a triangle is 114°. One of its two interior opposite angles is 46°. What is the other one (in degrees)?
  8. 8.The two shorter sides of a right-angled triangle are 10 cm and 24 cm. How long is the longest side (in cm)?
  9. 9.An exterior angle of a triangle is 120°. One of its two interior opposite angles is 65°. What is the other one (in degrees)?
  10. 10.Can a triangle have sides of 5 cm, 16 cm and 8 cm? (a) Yes (b) No
  11. 11.The longest side of a right-angled triangle is 39 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  12. 12.Can a triangle have sides of 10 cm, 20 cm and 12 cm? (a) Yes (b) No
  13. 13.The two shorter sides of a right-angled triangle are 15 cm and 20 cm. How long is the longest side (in cm)?
  14. 14.In an isosceles triangle, the two equal angles are 67° each. What is the third angle (in degrees)?
  15. 15.In triangle ABC, angle A = 32° and angle B = 30°. What is angle C (in degrees)?
  16. 16.An exterior angle of a triangle is 112°. One of its two interior opposite angles is 40°. What is the other one (in degrees)?
  17. 17.In triangle ABC, angle A = 30° and angle B = 73°. What is angle C (in degrees)?
  18. 18.The two interior opposite angles of a triangle are 40° and 31°. What is the exterior angle (in degrees)?
  19. 19.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (in degrees)?
  20. 20.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  21. 21.Can a triangle have sides of 3 cm, 12 cm and 17 cm? (a) Yes (b) No
  22. 22.In triangle ABC, angle A = 25° and angle B = 46°. What is angle C (in degrees)?
  23. 23.In an isosceles triangle, the angle between the two equal sides is 132°. What is each of the other two angles (in degrees)?
  24. 24.Can a triangle have sides of 11 cm, 5 cm and 8 cm? (a) No (b) Yes
  25. 25.The angles of a triangle are in the ratio 2 : 2 : 5. What is the smallest angle (in degrees)?
  26. 26.In a right-angled triangle, one of the other two angles is 68°. What is the third angle (in degrees)?
  27. 27.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?
  28. 28.The two interior opposite angles of a triangle are 52° and 70°. What is the exterior angle (in degrees)?
  29. 29.The two interior opposite angles of a triangle are 62° and 54°. What is the exterior angle (in degrees)?
  30. 30.Can a triangle have sides of 6 cm, 11 cm and 9 cm? (a) Yes (b) No
  31. 31.In a right-angled triangle, one of the other two angles is 22°. What is the third angle (in degrees)?
  32. 32.In triangle ABC, angle A = 36° and angle B = 77°. What is angle C (in degrees)?
  33. 33.In triangle ABC, angle A = 83° and angle B = 38°. What is angle C (in degrees)?
  34. 34.In triangle ABC, angle A = 51° and angle B = 43°. What is angle C (in degrees)?
  35. 35.An exterior angle of a triangle is 133°. One of its two interior opposite angles is 75°. What is the other one (in degrees)?
  36. 36.In a right-angled triangle, one of the other two angles is 13°. What is the third angle (in degrees)?
  37. 37.In triangle ABC, angle A = 60° and angle B = 83°. What is angle C (in degrees)?
  38. 38.Can a triangle have sides of 8 cm, 2 cm and 6 cm? (a) No (b) Yes
  39. 39.The two shorter sides of a right-angled triangle are 3 cm and 4 cm. How long is the longest side (in cm)?
  40. 40.In triangle ABC, angle A = 94° and angle B = 40°. What is angle C (in degrees)?

Answer key

  1. 64
  2. 88
  3. Yes
  4. 99
  5. 74
  6. 21
  7. 68
  8. 26
  9. 55
  10. No
  11. 36
  12. Yes
  13. 25
  14. 46
  15. 118
  16. 72
  17. 77
  18. 71
  19. 72
  20. 25
  21. No
  22. 109
  23. 24
  24. Yes
  25. 40
  26. 22
  27. 48
  28. 122
  29. 116
  30. Yes
  31. 68
  32. 67
  33. 59
  34. 86
  35. 58
  36. 77
  37. 37
  38. No
  39. 5
  40. 46

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