← Triangles: angle sum, exterior angle and Pythagoras lesson New set →

Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 721 · 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.Can a triangle have sides of 8 cm, 12 cm and 13 cm? (a) No (b) Yes
  2. 2.The two interior opposite angles of a triangle are 51° and 47°. What is the exterior angle (in degrees)?
  3. 3.In triangle ABC, angle A = 32° and angle B = 25°. What is angle C (in degrees)?
  4. 4.In triangle ABC, angle A = 54° and angle B = 63°. What is angle C (in degrees)?
  5. 5.In an isosceles triangle, the two equal angles are 52° each. What is the third angle (in degrees)?
  6. 6.In an isosceles triangle, the two equal angles are 22° each. What is the third angle (in degrees)?
  7. 7.In a right-angled triangle, one of the other two angles is 43°. What is the third angle (in degrees)?
  8. 8.The angles of a triangle are in the ratio 3 : 3 : 4. What is the smallest angle (in degrees)?
  9. 9.In triangle ABC, angle A = 80° and angle B = 59°. What is angle C (in degrees)?
  10. 10.The angles of a triangle are in the ratio 2 : 3 : 5. What is the smallest angle (in degrees)?
  11. 11.The longest side of a right-angled triangle is 13 cm and one of the other sides is 5 cm. How long is the third side (in cm)?
  12. 12.In an isosceles triangle, the angle between the two equal sides is 136°. What is each of the other two angles (in degrees)?
  13. 13.In a right-angled triangle, one of the other two angles is 28°. What is the third angle (in degrees)?
  14. 14.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)?
  15. 15.In triangle ABC, angle A = 37° and angle B = 111°. What is angle C (in degrees)?
  16. 16.In an isosceles triangle, the angle between the two equal sides is 22°. What is each of the other two angles (in degrees)?
  17. 17.The two interior opposite angles of a triangle are 57° and 22°. What is the exterior angle (in degrees)?
  18. 18.In triangle ABC, angle A = 51° and angle B = 46°. What is angle C (in degrees)?
  19. 19.In triangle ABC, angle A = 85° and angle B = 59°. What is angle C (in degrees)?
  20. 20.The two interior opposite angles of a triangle are 71° and 68°. What is the exterior angle (in degrees)?
  21. 21.In triangle ABC, angle A = 21° and angle B = 110°. What is angle C (in degrees)?
  22. 22.Can a triangle have sides of 7 cm, 13 cm and 4 cm? (a) No (b) Yes
  23. 23.The two shorter sides of a right-angled triangle are 20 cm and 15 cm. How long is the longest side (in cm)?
  24. 24.In triangle ABC, angle A = 73° and angle B = 31°. What is angle C (in degrees)?
  25. 25.In an isosceles triangle, the angle between the two equal sides is 106°. What is each of the other two angles (in degrees)?
  26. 26.In triangle ABC, angle A = 37° and angle B = 49°. What is angle C (in degrees)?
  27. 27.Can a triangle have sides of 16 cm, 3 cm and 10 cm? (a) Yes (b) No
  28. 28.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)?
  29. 29.The longest side of a right-angled triangle is 17 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  30. 30.In triangle ABC, angle A = 75° and angle B = 75°. What is angle C (in degrees)?
  31. 31.The angles of a triangle are in the ratio 1 : 2 : 6. What is the smallest angle (in degrees)?
  32. 32.In an isosceles triangle, the two equal angles are 53° each. What is the third angle (in degrees)?
  33. 33.Can a triangle have sides of 16 cm, 8 cm and 8 cm? (a) Yes (b) No
  34. 34.In an isosceles triangle, the angle between the two equal sides is 102°. What is each of the other two angles (in degrees)?
  35. 35.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  36. 36.In triangle ABC, angle A = 39° and angle B = 100°. What is angle C (in degrees)?
  37. 37.In a right-angled triangle, one of the other two angles is 22°. What is the third angle (in degrees)?
  38. 38.In triangle ABC, angle A = 30° and angle B = 47°. What is angle C (in degrees)?
  39. 39.In an isosceles triangle, the angle between the two equal sides is 74°. What is each of the other two angles (in degrees)?
  40. 40.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?

Answer key

  1. Yes
  2. 98
  3. 123
  4. 63
  5. 76
  6. 136
  7. 47
  8. 54
  9. 41
  10. 36
  11. 12
  12. 22
  13. 62
  14. 15
  15. 32
  16. 79
  17. 79
  18. 83
  19. 36
  20. 139
  21. 49
  22. No
  23. 25
  24. 76
  25. 37
  26. 94
  27. No
  28. 10
  29. 8
  30. 30
  31. 20
  32. 74
  33. No
  34. 39
  35. 90
  36. 41
  37. 68
  38. 103
  39. 53
  40. 36

Free maths worksheets lessons, practice and worksheets at talentjr.in/maths-worksheets