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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 925 · 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.The two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  2. 2.In an isosceles triangle, the angle between the two equal sides is 76°. What is each of the other two angles (in degrees)?
  3. 3.An exterior angle of a triangle is 76°. One of its two interior opposite angles is 46°. What is the other one (in degrees)?
  4. 4.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  5. 5.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  6. 6.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  7. 7.Can a triangle have sides of 11 cm, 10 cm and 18 cm? (a) No (b) Yes
  8. 8.The angles of a triangle are in the ratio 1 : 2 : 3. What is the smallest angle (in degrees)?
  9. 9.In a right-angled triangle, one of the other two angles is 34°. What is the third angle (in degrees)?
  10. 10.In a right-angled triangle, one of the other two angles is 44°. What is the third angle (in degrees)?
  11. 11.In an isosceles triangle, the two equal angles are 32° each. What is the third angle (in degrees)?
  12. 12.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  13. 13.In triangle ABC, angle A = 36° and angle B = 34°. What is angle C (in degrees)?
  14. 14.In a right-angled triangle, one of the other two angles is 55°. What is the third angle (in degrees)?
  15. 15.In a right-angled triangle, one of the other two angles is 25°. What is the third angle (in degrees)?
  16. 16.In triangle ABC, angle A = 58° and angle B = 31°. What is angle C (in degrees)?
  17. 17.Can a triangle have sides of 7 cm, 2 cm and 8 cm? (a) Yes (b) No
  18. 18.Can a triangle have sides of 11 cm, 16 cm and 8 cm? (a) Yes (b) No
  19. 19.An exterior angle of a triangle is 97°. One of its two interior opposite angles is 72°. What is the other one (in degrees)?
  20. 20.An exterior angle of a triangle is 93°. One of its two interior opposite angles is 37°. What is the other one (in degrees)?
  21. 21.An exterior angle of a triangle is 131°. One of its two interior opposite angles is 54°. What is the other one (in degrees)?
  22. 22.The longest side of a right-angled triangle is 10 cm and one of the other sides is 6 cm. How long is the third side (in cm)?
  23. 23.The two interior opposite angles of a triangle are 74° and 58°. What is the exterior angle (in degrees)?
  24. 24.An exterior angle of a triangle is 94°. One of its two interior opposite angles is 45°. What is the other one (in degrees)?
  25. 25.Can a triangle have sides of 8 cm, 6 cm and 15 cm? (a) No (b) Yes
  26. 26.In triangle ABC, angle A = 84° and angle B = 58°. What is angle C (in degrees)?
  27. 27.In triangle ABC, angle A = 84° and angle B = 63°. What is angle C (in degrees)?
  28. 28.In an isosceles triangle, the angle between the two equal sides is 156°. What is each of the other two angles (in degrees)?
  29. 29.The two interior opposite angles of a triangle are 44° and 55°. What is the exterior angle (in degrees)?
  30. 30.Can a triangle have sides of 1 cm, 9 cm and 9 cm? (a) Yes (b) No
  31. 31.In triangle ABC, angle A = 42° and angle B = 97°. What is angle C (in degrees)?
  32. 32.In triangle ABC, angle A = 28° and angle B = 92°. What is angle C (in degrees)?
  33. 33.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  34. 34.In an isosceles triangle, the angle between the two equal sides is 120°. What is each of the other two angles (in degrees)?
  35. 35.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)?
  36. 36.Can a triangle have sides of 8 cm, 8 cm and 2 cm? (a) Yes (b) No
  37. 37.An exterior angle of a triangle is 100°. One of its two interior opposite angles is 23°. What is the other one (in degrees)?
  38. 38.In triangle ABC, angle A = 96° and angle B = 45°. What is angle C (in degrees)?
  39. 39.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 23°. What is the third angle (in degrees)?

Answer key

  1. 39
  2. 52
  3. 30
  4. 72
  5. 120
  6. 90
  7. Yes
  8. 30
  9. 56
  10. 46
  11. 116
  12. 25
  13. 110
  14. 35
  15. 65
  16. 91
  17. Yes
  18. Yes
  19. 25
  20. 56
  21. 77
  22. 8
  23. 132
  24. 49
  25. No
  26. 38
  27. 33
  28. 12
  29. 99
  30. Yes
  31. 41
  32. 60
  33. 20
  34. 30
  35. 15
  36. Yes
  37. 77
  38. 39
  39. 40
  40. 67

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