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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 80 · 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 = 34° and angle B = 30°. What is angle C (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.In triangle ABC, angle A = 56° and angle B = 72°. What is angle C (in degrees)?
  4. 4.The two interior opposite angles of a triangle are 55° and 46°. What is the exterior angle (in degrees)?
  5. 5.Can a triangle have sides of 11 cm, 6 cm and 10 cm? (a) No (b) Yes
  6. 6.In a right-angled triangle, one of the other two angles is 67°. What is the third angle (in degrees)?
  7. 7.In a right-angled triangle, one of the other two angles is 69°. What is the third angle (in degrees)?
  8. 8.In triangle ABC, angle A = 63° and angle B = 27°. What is angle C (in degrees)?
  9. 9.Can a triangle have sides of 9 cm, 19 cm and 8 cm? (a) No (b) Yes
  10. 10.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)?
  11. 11.Can a triangle have sides of 6 cm, 12 cm and 21 cm? (a) Yes (b) No
  12. 12.The two interior opposite angles of a triangle are 38° and 25°. What is the exterior angle (in degrees)?
  13. 13.In a right-angled triangle, one of the other two angles is 29°. What is the third angle (in degrees)?
  14. 14.The two shorter sides of a right-angled triangle are 10 cm and 24 cm. How long is the longest side (in cm)?
  15. 15.The angles of a triangle are in the ratio 2 : 7 : 9. What is the biggest angle (in degrees)?
  16. 16.The two interior opposite angles of a triangle are 65° and 66°. What is the exterior angle (in degrees)?
  17. 17.In triangle ABC, angle A = 75° and angle B = 44°. What is angle C (in degrees)?
  18. 18.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)?
  19. 19.In a right-angled triangle, one of the other two angles is 21°. What is the third angle (in degrees)?
  20. 20.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  21. 21.In a right-angled triangle, one of the other two angles is 66°. What is the third angle (in degrees)?
  22. 22.In triangle ABC, angle A = 71° and angle B = 27°. What is angle C (in degrees)?
  23. 23.The two interior opposite angles of a triangle are 53° and 58°. What is the exterior angle (in degrees)?
  24. 24.In triangle ABC, angle A = 25° and angle B = 29°. What is angle C (in degrees)?
  25. 25.The two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  26. 26.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  27. 27.In triangle ABC, angle A = 50° and angle B = 28°. What is angle C (in degrees)?
  28. 28.In an isosceles triangle, the two equal angles are 81° each. What is the third angle (in degrees)?
  29. 29.In triangle ABC, angle A = 86° and angle B = 34°. What is angle C (in degrees)?
  30. 30.In triangle ABC, angle A = 97° and angle B = 62°. What is angle C (in degrees)?
  31. 31.In an isosceles triangle, the two equal angles are 59° each. What is the third angle (in degrees)?
  32. 32.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)?
  33. 33.Can a triangle have sides of 11 cm, 23 cm and 10 cm? (a) No (b) Yes
  34. 34.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  35. 35.In a right-angled triangle, one of the other two angles is 64°. What is the third angle (in degrees)?
  36. 36.Can a triangle have sides of 10 cm, 7 cm and 4 cm? (a) Yes (b) No
  37. 37.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?
  38. 38.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  39. 39.In an isosceles triangle, the angle between the two equal sides is 98°. What is each of the other two angles (in degrees)?
  40. 40.The two interior opposite angles of a triangle are 56° and 24°. What is the exterior angle (in degrees)?

Answer key

  1. 116
  2. 90
  3. 52
  4. 101
  5. Yes
  6. 23
  7. 21
  8. 90
  9. No
  10. 36
  11. No
  12. 63
  13. 61
  14. 26
  15. 90
  16. 131
  17. 61
  18. 7
  19. 69
  20. 25
  21. 24
  22. 82
  23. 111
  24. 126
  25. 39
  26. 25
  27. 102
  28. 18
  29. 60
  30. 21
  31. 62
  32. 24
  33. No
  34. 72
  35. 26
  36. Yes
  37. 50
  38. 100
  39. 41
  40. 80

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