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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 365 · 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 an isosceles triangle, the angle between the two equal sides is 98°. What is each of the other two angles (in degrees)?
  2. 2.The angles of a triangle are in the ratio 1 : 2 : 3. What is the biggest angle (in degrees)?
  3. 3.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  4. 4.In triangle ABC, angle A = 53° and angle B = 36°. What is angle C (in degrees)?
  5. 5.In a right-angled triangle, one of the other two angles is 34°. What is the third angle (in degrees)?
  6. 6.In an isosceles triangle, the angle between the two equal sides is 20°. What is each of the other two angles (in degrees)?
  7. 7.The two interior opposite angles of a triangle are 43° and 41°. What is the exterior angle (in degrees)?
  8. 8.In a right-angled triangle, one of the other two angles is 61°. What is the third angle (in degrees)?
  9. 9.An exterior angle of a triangle is 54°. One of its two interior opposite angles is 34°. What is the other one (in degrees)?
  10. 10.In an isosceles triangle, the angle between the two equal sides is 60°. What is each of the other two angles (in degrees)?
  11. 11.An exterior angle of a triangle is 64°. One of its two interior opposite angles is 28°. What is the other one (in degrees)?
  12. 12.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  13. 13.In triangle ABC, angle A = 55° and angle B = 28°. What is angle C (in degrees)?
  14. 14.In triangle ABC, angle A = 27° and angle B = 71°. What is angle C (in degrees)?
  15. 15.The two shorter sides of a right-angled triangle are 24 cm and 10 cm. How long is the longest side (in cm)?
  16. 16.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)?
  17. 17.In a right-angled triangle, one of the other two angles is 17°. What is the third angle (in degrees)?
  18. 18.In a right-angled triangle, one of the other two angles is 49°. What is the third angle (in degrees)?
  19. 19.In a right-angled triangle, one of the other two angles is 31°. What is the third angle (in degrees)?
  20. 20.An exterior angle of a triangle is 150°. One of its two interior opposite angles is 76°. What is the other one (in degrees)?
  21. 21.The two interior opposite angles of a triangle are 51° and 68°. What is the exterior angle (in degrees)?
  22. 22.The two interior opposite angles of a triangle are 59° and 33°. What is the exterior angle (in degrees)?
  23. 23.In a right-angled triangle, one of the other two angles is 48°. What is the third angle (in degrees)?
  24. 24.In a right-angled triangle, one of the other two angles is 46°. What is the third angle (in degrees)?
  25. 25.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  26. 26.Can a triangle have sides of 12 cm, 9 cm and 24 cm? (a) No (b) Yes
  27. 27.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?
  28. 28.In triangle ABC, angle A = 36° and angle B = 104°. What is angle C (in degrees)?
  29. 29.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  30. 30.The two shorter sides of a right-angled triangle are 9 cm and 12 cm. How long is the longest side (in cm)?
  31. 31.The longest side of a right-angled triangle is 17 cm and one of the other sides is 8 cm. How long is the third side (in cm)?
  32. 32.In an isosceles triangle, the angle between the two equal sides is 28°. What is each of the other two angles (in degrees)?
  33. 33.The longest side of a right-angled triangle is 30 cm and one of the other sides is 24 cm. How long is the third side (in cm)?
  34. 34.The longest side of a right-angled triangle is 26 cm and one of the other sides is 10 cm. How long is the third side (in cm)?
  35. 35.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)?
  36. 36.In a right-angled triangle, one of the other two angles is 29°. What is the third angle (in degrees)?
  37. 37.Can a triangle have sides of 8 cm, 20 cm and 12 cm? (a) Yes (b) No
  38. 38.Can a triangle have sides of 20 cm, 10 cm and 10 cm? (a) No (b) Yes
  39. 39.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  40. 40.Can a triangle have sides of 9 cm, 22 cm and 12 cm? (a) Yes (b) No

Answer key

  1. 41
  2. 90
  3. 80
  4. 91
  5. 56
  6. 80
  7. 84
  8. 29
  9. 20
  10. 60
  11. 36
  12. 17
  13. 97
  14. 82
  15. 26
  16. 7
  17. 73
  18. 41
  19. 59
  20. 74
  21. 119
  22. 92
  23. 42
  24. 44
  25. 90
  26. No
  27. 50
  28. 40
  29. 20
  30. 15
  31. 15
  32. 76
  33. 18
  34. 24
  35. 36
  36. 61
  37. No
  38. No
  39. 40
  40. No

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