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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 207 · 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.

NameDateTime takenScore ___ / 40
  1. 1.In an isosceles triangle, the angle between the two equal sides is 128°. What is each of the other two angles (in degrees)?
  2. 2.An exterior angle of a triangle is 82°. One of its two interior opposite angles is 37°. What is the other one (in degrees)?
  3. 3.Can a triangle have sides of 22 cm, 10 cm and 10 cm? (a) Yes (b) No
  4. 4.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  5. 5.An exterior angle of a triangle is 92°. One of its two interior opposite angles is 58°. What is the other one (in degrees)?
  6. 6.Can a triangle have sides of 13 cm, 11 cm and 10 cm? (a) Yes (b) No
  7. 7.In a right-angled triangle, one of the other two angles is 32°. What is the third angle (in degrees)?
  8. 8.In an isosceles triangle, the angle between the two equal sides is 76°. What is each of the other two angles (in degrees)?
  9. 9.In a right-angled triangle, one of the other two angles is 52°. What is the third angle (in degrees)?
  10. 10.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  11. 11.In triangle ABC, angle A = 62° and angle B = 69°. What is angle C (in degrees)?
  12. 12.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  13. 13.In triangle ABC, angle A = 88° and angle B = 26°. What is angle C (in degrees)?
  14. 14.In a right-angled triangle, one of the other two angles is 17°. What is the third angle (in degrees)?
  15. 15.In an isosceles triangle, the two equal angles are 79° each. What is the third angle (in degrees)?
  16. 16.Can a triangle have sides of 10 cm, 17 cm and 3 cm? (a) No (b) Yes
  17. 17.In a right-angled triangle, one of the other two angles is 71°. What is the third angle (in degrees)?
  18. 18.In triangle ABC, angle A = 92° and angle B = 32°. What is angle C (in degrees)?
  19. 19.Can a triangle have sides of 8 cm, 22 cm and 11 cm? (a) No (b) Yes
  20. 20.In triangle ABC, angle A = 25° and angle B = 95°. What is angle C (in degrees)?
  21. 21.In an isosceles triangle, the angle between the two equal sides is 148°. What is each of the other two angles (in degrees)?
  22. 22.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  23. 23.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (in degrees)?
  24. 24.In an isosceles triangle, the angle between the two equal sides is 116°. What is each of the other two angles (in degrees)?
  25. 25.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)?
  26. 26.In a right-angled triangle, one of the other two angles is 27°. What is the third angle (in degrees)?
  27. 27.An exterior angle of a triangle is 139°. One of its two interior opposite angles is 59°. What is the other one (in degrees)?
  28. 28.In triangle ABC, angle A = 32° and angle B = 40°. What is angle C (in degrees)?
  29. 29.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  30. 30.An exterior angle of a triangle is 102°. One of its two interior opposite angles is 70°. What is the other one (in degrees)?
  31. 31.In an isosceles triangle, the two equal angles are 74° each. What is the third angle (in degrees)?
  32. 32.In an isosceles triangle, the two equal angles are 22° each. What is the third angle (in degrees)?
  33. 33.In a right-angled triangle, one of the other two angles is 65°. What is the third angle (in degrees)?
  34. 34.Can a triangle have sides of 9 cm, 21 cm and 7 cm? (a) No (b) Yes
  35. 35.In a right-angled triangle, one of the other two angles is 23°. What is the third angle (in degrees)?
  36. 36.An exterior angle of a triangle is 141°. One of its two interior opposite angles is 67°. What is the other one (in degrees)?
  37. 37.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  38. 38.The two interior opposite angles of a triangle are 41° and 30°. What is the exterior angle (in degrees)?
  39. 39.In triangle ABC, angle A = 79° and angle B = 60°. What is angle C (in degrees)?
  40. 40.In an isosceles triangle, the angle between the two equal sides is 80°. What is each of the other two angles (in degrees)?

Answer key

  1. 26
  2. 45
  3. No
  4. 100
  5. 34
  6. Yes
  7. 58
  8. 52
  9. 38
  10. 18
  11. 49
  12. 40
  13. 66
  14. 73
  15. 22
  16. No
  17. 19
  18. 56
  19. No
  20. 60
  21. 16
  22. 80
  23. 72
  24. 32
  25. 24
  26. 63
  27. 80
  28. 108
  29. 45
  30. 32
  31. 32
  32. 136
  33. 25
  34. No
  35. 67
  36. 74
  37. 25
  38. 71
  39. 41
  40. 50

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