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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 815 · 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 a right-angled triangle, one of the other two angles is 13°. What is the third angle (in degrees)?
  2. 2.In an isosceles triangle, the angle between the two equal sides is 58°. What is each of the other two angles (in degrees)?
  3. 3.In a right-angled triangle, one of the other two angles is 50°. What is the third angle (in degrees)?
  4. 4.In an isosceles triangle, the two equal angles are 62° each. What is the third angle (in degrees)?
  5. 5.An exterior angle of a triangle is 80°. One of its two interior opposite angles is 50°. What is the other one (in degrees)?
  6. 6.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  7. 7.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  8. 8.In an isosceles triangle, the two equal angles are 24° each. What is the third angle (in degrees)?
  9. 9.In triangle ABC, angle A = 73° and angle B = 82°. What is angle C (in degrees)?
  10. 10.In a right-angled triangle, one of the other two angles is 35°. What is the third angle (in degrees)?
  11. 11.An exterior angle of a triangle is 128°. One of its two interior opposite angles is 68°. What is the other one (in degrees)?
  12. 12.In triangle ABC, angle A = 87° and angle B = 34°. What is angle C (in degrees)?
  13. 13.In an isosceles triangle, the angle between the two equal sides is 146°. What is each of the other two angles (in degrees)?
  14. 14.In triangle ABC, angle A = 93° and angle B = 42°. What is angle C (in degrees)?
  15. 15.Can a triangle have sides of 3 cm, 8 cm and 7 cm? (a) No (b) Yes
  16. 16.An exterior angle of a triangle is 69°. One of its two interior opposite angles is 43°. What is the other one (in degrees)?
  17. 17.An exterior angle of a triangle is 122°. One of its two interior opposite angles is 53°. What is the other one (in degrees)?
  18. 18.In an isosceles triangle, the two equal angles are 84° each. What is the third angle (in degrees)?
  19. 19.In an isosceles triangle, the angle between the two equal sides is 110°. What is each of the other two angles (in degrees)?
  20. 20.In triangle ABC, angle A = 88° and angle B = 67°. What is angle C (in degrees)?
  21. 21.In an isosceles triangle, the angle between the two equal sides is 80°. What is each of the other two angles (in degrees)?
  22. 22.In a right-angled triangle, one of the other two angles is 11°. What is the third angle (in degrees)?
  23. 23.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  24. 24.Can a triangle have sides of 10 cm, 9 cm and 8 cm? (a) Yes (b) No
  25. 25.In triangle ABC, angle A = 23° and angle B = 108°. What is angle C (in degrees)?
  26. 26.The angles of a triangle are in the ratio 1 : 2 : 3. What is the biggest angle (in degrees)?
  27. 27.In triangle ABC, angle A = 26° and angle B = 35°. What is angle C (in degrees)?
  28. 28.In an isosceles triangle, the two equal angles are 54° each. What is the third angle (in degrees)?
  29. 29.Can a triangle have sides of 7 cm, 19 cm and 9 cm? (a) Yes (b) No
  30. 30.In an isosceles triangle, the angle between the two equal sides is 148°. What is each of the other two angles (in degrees)?
  31. 31.Can a triangle have sides of 10 cm, 15 cm and 2 cm? (a) Yes (b) No
  32. 32.In triangle ABC, angle A = 21° and angle B = 46°. What is angle C (in degrees)?
  33. 33.Can a triangle have sides of 20 cm, 8 cm and 9 cm? (a) No (b) Yes
  34. 34.An exterior angle of a triangle is 77°. One of its two interior opposite angles is 26°. What is the other one (in degrees)?
  35. 35.In triangle ABC, angle A = 22° and angle B = 59°. What is angle C (in degrees)?
  36. 36.Can a triangle have sides of 18 cm, 9 cm and 9 cm? (a) Yes (b) No
  37. 37.The two interior opposite angles of a triangle are 52° and 38°. What is the exterior angle (in degrees)?
  38. 38.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  39. 39.An exterior angle of a triangle is 102°. One of its two interior opposite angles is 41°. What is the other one (in degrees)?
  40. 40.Can a triangle have sides of 4 cm, 5 cm and 14 cm? (a) No (b) Yes

Answer key

  1. 77
  2. 61
  3. 40
  4. 56
  5. 30
  6. 100
  7. 120
  8. 132
  9. 25
  10. 55
  11. 60
  12. 59
  13. 17
  14. 45
  15. Yes
  16. 26
  17. 69
  18. 12
  19. 35
  20. 25
  21. 50
  22. 79
  23. 18
  24. Yes
  25. 49
  26. 90
  27. 119
  28. 72
  29. No
  30. 16
  31. No
  32. 113
  33. No
  34. 51
  35. 99
  36. No
  37. 90
  38. 20
  39. 61
  40. No

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