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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 219 · 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 = 92° and angle B = 34°. What is angle C (in degrees)?
  2. 2.In a right-angled triangle, one of the other two angles is 22°. What is the third angle (in degrees)?
  3. 3.In triangle ABC, angle A = 42° and angle B = 53°. What is angle C (in degrees)?
  4. 4.The two interior opposite angles of a triangle are 79° and 35°. What is the exterior angle (in degrees)?
  5. 5.In a right-angled triangle, one of the other two angles is 45°. What is the third angle (in degrees)?
  6. 6.The two interior opposite angles of a triangle are 64° and 24°. What is the exterior angle (in degrees)?
  7. 7.Can a triangle have sides of 11 cm, 9 cm and 8 cm? (a) No (b) Yes
  8. 8.The two interior opposite angles of a triangle are 35° and 48°. What is the exterior angle (in degrees)?
  9. 9.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  10. 10.In an isosceles triangle, the angle between the two equal sides is 36°. What is each of the other two angles (in degrees)?
  11. 11.The two interior opposite angles of a triangle are 22° and 40°. What is the exterior angle (in degrees)?
  12. 12.The longest side of a right-angled triangle is 26 cm and one of the other sides is 10 cm. How long is the third side (in cm)?
  13. 13.An exterior angle of a triangle is 89°. One of its two interior opposite angles is 57°. What is the other one (in degrees)?
  14. 14.In a right-angled triangle, one of the other two angles is 26°. What is the third angle (in degrees)?
  15. 15.An exterior angle of a triangle is 82°. One of its two interior opposite angles is 50°. What is the other one (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.The two shorter sides of a right-angled triangle are 12 cm and 5 cm. How long is the longest side (in cm)?
  18. 18.In an isosceles triangle, the angle between the two equal sides is 92°. What is each of the other two angles (in degrees)?
  19. 19.In a right-angled triangle, one of the other two angles is 17°. What is the third angle (in degrees)?
  20. 20.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)?
  21. 21.In a right-angled triangle, one of the other two angles is 69°. What is the third angle (in degrees)?
  22. 22.The two shorter sides of a right-angled triangle are 12 cm and 9 cm. How long is the longest side (in cm)?
  23. 23.The two interior opposite angles of a triangle are 53° and 37°. What is the exterior angle (in degrees)?
  24. 24.In an isosceles triangle, the two equal angles are 32° each. What is the third angle (in degrees)?
  25. 25.In triangle ABC, angle A = 53° and angle B = 37°. What is angle C (in degrees)?
  26. 26.An exterior angle of a triangle is 63°. One of its two interior opposite angles is 28°. What is the other one (in degrees)?
  27. 27.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (in degrees)?
  28. 28.The angles of a triangle are in the ratio 2 : 3 : 5. What is the smallest angle (in degrees)?
  29. 29.In triangle ABC, angle A = 28° and angle B = 69°. What is angle C (in degrees)?
  30. 30.An exterior angle of a triangle is 100°. One of its two interior opposite angles is 30°. What is the other one (in degrees)?
  31. 31.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  32. 32.The two interior opposite angles of a triangle are 70° and 27°. What is the exterior angle (in degrees)?
  33. 33.In triangle ABC, angle A = 63° and angle B = 46°. What is angle C (in degrees)?
  34. 34.In an isosceles triangle, the two equal angles are 59° each. What is the third angle (in degrees)?
  35. 35.In triangle ABC, angle A = 33° and angle B = 31°. What is angle C (in degrees)?
  36. 36.In an isosceles triangle, the two equal angles are 37° each. What is the third angle (in degrees)?
  37. 37.The two interior opposite angles of a triangle are 67° and 35°. What is the exterior angle (in degrees)?
  38. 38.In a right-angled triangle, one of the other two angles is 52°. What is the third angle (in degrees)?
  39. 39.The two interior opposite angles of a triangle are 36° and 63°. What is the exterior angle (in degrees)?
  40. 40.In an isosceles triangle, the angle between the two equal sides is 94°. What is each of the other two angles (in degrees)?

Answer key

  1. 54
  2. 68
  3. 85
  4. 114
  5. 45
  6. 88
  7. Yes
  8. 83
  9. 25
  10. 72
  11. 62
  12. 24
  13. 32
  14. 64
  15. 32
  16. 20
  17. 13
  18. 44
  19. 73
  20. 15
  21. 21
  22. 15
  23. 90
  24. 116
  25. 90
  26. 35
  27. 72
  28. 36
  29. 83
  30. 70
  31. 25
  32. 97
  33. 71
  34. 62
  35. 116
  36. 106
  37. 102
  38. 38
  39. 99
  40. 43

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