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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 540 · 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 angles of a triangle are in the ratio 1 : 2 : 3. What is the smallest angle (in degrees)?
  2. 2.Can a triangle have sides of 24 cm, 10 cm and 12 cm? (a) Yes (b) No
  3. 3.The two interior opposite angles of a triangle are 48° and 68°. What is the exterior angle (in degrees)?
  4. 4.The angles of a triangle are in the ratio 1 : 2 : 3. What is the biggest angle (in degrees)?
  5. 5.Can a triangle have sides of 7 cm, 9 cm and 16 cm? (a) Yes (b) No
  6. 6.In an isosceles triangle, the two equal angles are 46° each. What is the third angle (in degrees)?
  7. 7.In a right-angled triangle, one of the other two angles is 45°. What is the third angle (in degrees)?
  8. 8.In triangle ABC, angle A = 65° and angle B = 94°. What is angle C (in degrees)?
  9. 9.In triangle ABC, angle A = 42° and angle B = 103°. What is angle C (in degrees)?
  10. 10.Can a triangle have sides of 7 cm, 7 cm and 18 cm? (a) Yes (b) No
  11. 11.The two interior opposite angles of a triangle are 69° and 24°. What is the exterior angle (in degrees)?
  12. 12.In an isosceles triangle, the two equal angles are 67° each. What is the third angle (in degrees)?
  13. 13.Can a triangle have sides of 11 cm, 4 cm and 16 cm? (a) No (b) Yes
  14. 14.Can a triangle have sides of 2 cm, 14 cm and 11 cm? (a) No (b) Yes
  15. 15.In an isosceles triangle, the angle between the two equal sides is 112°. What is each of the other two angles (in degrees)?
  16. 16.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  17. 17.Can a triangle have sides of 7 cm, 6 cm and 4 cm? (a) Yes (b) No
  18. 18.Can a triangle have sides of 16 cm, 3 cm and 11 cm? (a) Yes (b) No
  19. 19.In a right-angled triangle, one of the other two angles is 63°. What is the third angle (in degrees)?
  20. 20.In an isosceles triangle, the angle between the two equal sides is 144°. What is each of the other two angles (in degrees)?
  21. 21.In a right-angled triangle, one of the other two angles is 59°. What is the third angle (in degrees)?
  22. 22.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  23. 23.Can a triangle have sides of 10 cm, 2 cm and 9 cm? (a) Yes (b) No
  24. 24.An exterior angle of a triangle is 88°. One of its two interior opposite angles is 67°. What is the other one (in degrees)?
  25. 25.Can a triangle have sides of 12 cm, 4 cm and 10 cm? (a) Yes (b) No
  26. 26.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)?
  27. 27.In an isosceles triangle, the two equal angles are 84° each. What is the third angle (in degrees)?
  28. 28.An exterior angle of a triangle is 107°. One of its two interior opposite angles is 46°. What is the other one (in degrees)?
  29. 29.An exterior angle of a triangle is 122°. One of its two interior opposite angles is 75°. What is the other one (in degrees)?
  30. 30.In a right-angled triangle, one of the other two angles is 11°. What is the third angle (in degrees)?
  31. 31.In triangle ABC, angle A = 25° and angle B = 73°. What is angle C (in degrees)?
  32. 32.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  33. 33.In a right-angled triangle, one of the other two angles is 21°. What is the third angle (in degrees)?
  34. 34.An exterior angle of a triangle is 99°. One of its two interior opposite angles is 29°. What is the other one (in degrees)?
  35. 35.Can a triangle have sides of 3 cm, 12 cm and 11 cm? (a) Yes (b) No
  36. 36.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (in degrees)?
  37. 37.In an isosceles triangle, the two equal angles are 48° each. What is the third angle (in degrees)?
  38. 38.Can a triangle have sides of 2 cm, 4 cm and 5 cm? (a) No (b) Yes
  39. 39.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?
  40. 40.The angles of a triangle are in the ratio 3 : 3 : 4. What is the smallest angle (in degrees)?

Answer key

  1. 30
  2. No
  3. 116
  4. 90
  5. No
  6. 88
  7. 45
  8. 21
  9. 35
  10. No
  11. 93
  12. 46
  13. No
  14. No
  15. 34
  16. 20
  17. Yes
  18. No
  19. 27
  20. 18
  21. 31
  22. 17
  23. Yes
  24. 21
  25. Yes
  26. 15
  27. 12
  28. 61
  29. 47
  30. 79
  31. 82
  32. 100
  33. 69
  34. 70
  35. Yes
  36. 72
  37. 84
  38. Yes
  39. 48
  40. 54

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