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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 82 · 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 6 cm, 10 cm and 11 cm? (a) No (b) Yes
  2. 2.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  3. 3.An exterior angle of a triangle is 103°. One of its two interior opposite angles is 71°. What is the other one (in degrees)?
  4. 4.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)?
  5. 5.In an isosceles triangle, the two equal angles are 64° each. What is the third angle (in degrees)?
  6. 6.In triangle ABC, angle A = 88° and angle B = 50°. What is angle C (in degrees)?
  7. 7.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  8. 8.In an isosceles triangle, the angle between the two equal sides is 142°. What is each of the other two angles (in degrees)?
  9. 9.An exterior angle of a triangle is 105°. One of its two interior opposite angles is 37°. What is the other one (in degrees)?
  10. 10.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  11. 11.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?
  12. 12.In a right-angled triangle, one of the other two angles is 34°. What is the third angle (in degrees)?
  13. 13.The longest side of a right-angled triangle is 5 cm and one of the other sides is 4 cm. How long is the third side (in cm)?
  14. 14.The angles of a triangle are in the ratio 1 : 2 : 3. What is the smallest angle (in degrees)?
  15. 15.In an isosceles triangle, the angle between the two equal sides is 46°. What is each of the other two angles (in degrees)?
  16. 16.In triangle ABC, angle A = 33° and angle B = 79°. What is angle C (in degrees)?
  17. 17.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  18. 18.In a right-angled triangle, one of the other two angles is 29°. What is the third angle (in degrees)?
  19. 19.In triangle ABC, angle A = 28° and angle B = 93°. What is angle C (in degrees)?
  20. 20.In a right-angled triangle, one of the other two angles is 40°. What is the third angle (in degrees)?
  21. 21.Can a triangle have sides of 9 cm, 19 cm and 8 cm? (a) No (b) Yes
  22. 22.In an isosceles triangle, the two equal angles are 26° each. What is the third angle (in degrees)?
  23. 23.Can a triangle have sides of 8 cm, 9 cm and 22 cm? (a) No (b) Yes
  24. 24.Can a triangle have sides of 23 cm, 9 cm and 11 cm? (a) Yes (b) No
  25. 25.In triangle ABC, angle A = 91° and angle B = 64°. What is angle C (in degrees)?
  26. 26.In a right-angled triangle, one of the other two angles is 78°. What is the third angle (in degrees)?
  27. 27.In a right-angled triangle, one of the other two angles is 44°. What is the third angle (in degrees)?
  28. 28.In triangle ABC, angle A = 62° and angle B = 85°. What is angle C (in degrees)?
  29. 29.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  30. 30.In an isosceles triangle, the angle between the two equal sides is 72°. What is each of the other two angles (in degrees)?
  31. 31.In a right-angled triangle, one of the other two angles is 14°. What is the third angle (in degrees)?
  32. 32.In a right-angled triangle, one of the other two angles is 23°. What is the third angle (in degrees)?
  33. 33.Can a triangle have sides of 3 cm, 4 cm and 9 cm? (a) No (b) Yes
  34. 34.In an isosceles triangle, the angle between the two equal sides is 48°. What is each of the other two angles (in degrees)?
  35. 35.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  36. 36.The two shorter sides of a right-angled triangle are 18 cm and 24 cm. How long is the longest side (in cm)?
  37. 37.In an isosceles triangle, the two equal angles are 39° each. What is the third angle (in degrees)?
  38. 38.In a right-angled triangle, one of the other two angles is 26°. What is the third angle (in degrees)?
  39. 39.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)?
  40. 40.Can a triangle have sides of 9 cm, 18 cm and 8 cm? (a) No (b) Yes

Answer key

  1. Yes
  2. 90
  3. 32
  4. 24
  5. 52
  6. 42
  7. 80
  8. 19
  9. 68
  10. 120
  11. 48
  12. 56
  13. 3
  14. 30
  15. 67
  16. 68
  17. 90
  18. 61
  19. 59
  20. 50
  21. No
  22. 128
  23. No
  24. No
  25. 25
  26. 12
  27. 46
  28. 33
  29. 20
  30. 54
  31. 76
  32. 67
  33. No
  34. 66
  35. 75
  36. 30
  37. 102
  38. 64
  39. 7
  40. No

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