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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 990 · 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 8 cm. How long is the longest side (in cm)?
  2. 2.In an isosceles triangle, the two equal angles are 81° each. What is the third angle (in degrees)?
  3. 3.The two interior opposite angles of a triangle are 75° and 66°. What is the exterior angle (in degrees)?
  4. 4.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  5. 5.The angles of a triangle are in the ratio 1 : 2 : 2. What is the smallest angle (in degrees)?
  6. 6.An exterior angle of a triangle is 96°. One of its two interior opposite angles is 36°. What is the other one (in degrees)?
  7. 7.The two interior opposite angles of a triangle are 28° and 34°. What is the exterior angle (in degrees)?
  8. 8.An exterior angle of a triangle is 101°. One of its two interior opposite angles is 25°. What is the other one (in degrees)?
  9. 9.The angles of a triangle are in the ratio 1 : 2 : 6. What is the smallest angle (in degrees)?
  10. 10.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest 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.Can a triangle have sides of 10 cm, 12 cm and 10 cm? (a) Yes (b) No
  13. 13.Can a triangle have sides of 4 cm, 5 cm and 6 cm? (a) No (b) Yes
  14. 14.An exterior angle of a triangle is 116°. One of its two interior opposite angles is 79°. What is the other one (in degrees)?
  15. 15.In triangle ABC, angle A = 42° and angle B = 22°. What is angle C (in degrees)?
  16. 16.The two shorter sides of a right-angled triangle are 6 cm and 8 cm. How long is the longest side (in cm)?
  17. 17.The longest side of a right-angled triangle is 25 cm and one of the other sides is 20 cm. How long is the third side (in cm)?
  18. 18.The angles of a triangle are in the ratio 1 : 2 : 2. What is the biggest angle (in degrees)?
  19. 19.In a right-angled triangle, one of the other two angles is 57°. What is the third angle (in degrees)?
  20. 20.In a right-angled triangle, one of the other two angles is 72°. What is the third angle (in degrees)?
  21. 21.The angles of a triangle are in the ratio 1 : 2 : 3. What is the smallest angle (in degrees)?
  22. 22.In an isosceles triangle, the two equal angles are 34° each. What is the third angle (in degrees)?
  23. 23.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  24. 24.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  25. 25.In a right-angled triangle, one of the other two angles is 16°. What is the third angle (in degrees)?
  26. 26.In an isosceles triangle, the two equal angles are 25° each. What is the third angle (in degrees)?
  27. 27.In a right-angled triangle, one of the other two angles is 75°. What is the third angle (in degrees)?
  28. 28.In an isosceles triangle, the angle between the two equal sides is 88°. What is each of the other two angles (in degrees)?
  29. 29.An exterior angle of a triangle is 133°. One of its two interior opposite angles is 63°. What is the other one (in degrees)?
  30. 30.In triangle ABC, angle A = 23° and angle B = 103°. What is angle C (in degrees)?
  31. 31.An exterior angle of a triangle is 108°. One of its two interior opposite angles is 75°. What is the other one (in degrees)?
  32. 32.In triangle ABC, angle A = 46° and angle B = 20°. What is angle C (in degrees)?
  33. 33.The longest side of a right-angled triangle is 26 cm and one of the other sides is 24 cm. How long is the third side (in cm)?
  34. 34.An exterior angle of a triangle is 149°. One of its two interior opposite angles is 80°. What is the other one (in degrees)?
  35. 35.In an isosceles triangle, the two equal angles are 28° each. What is the third angle (in degrees)?
  36. 36.Can a triangle have sides of 4 cm, 10 cm and 4 cm? (a) No (b) Yes
  37. 37.In a right-angled triangle, one of the other two angles is 64°. What is the third angle (in degrees)?
  38. 38.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  39. 39.In an isosceles triangle, the angle between the two equal sides is 142°. What is each of the other two angles (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 32°. What is the third angle (in degrees)?

Answer key

  1. 17
  2. 18
  3. 141
  4. 90
  5. 36
  6. 60
  7. 62
  8. 76
  9. 20
  10. 72
  11. 116
  12. Yes
  13. Yes
  14. 37
  15. 116
  16. 10
  17. 15
  18. 72
  19. 33
  20. 18
  21. 30
  22. 112
  23. 40
  24. 72
  25. 74
  26. 130
  27. 15
  28. 46
  29. 70
  30. 54
  31. 33
  32. 114
  33. 10
  34. 69
  35. 124
  36. No
  37. 26
  38. 45
  39. 19
  40. 58

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