← 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 194 · 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.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  2. 2.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)?
  3. 3.In triangle ABC, angle A = 60° and angle B = 39°. What is angle C (in degrees)?
  4. 4.Can a triangle have sides of 16 cm, 5 cm and 10 cm? (a) No (b) Yes
  5. 5.In an isosceles triangle, the two equal angles are 48° each. What is the third angle (in degrees)?
  6. 6.Can a triangle have sides of 2 cm, 3 cm and 2 cm? (a) No (b) Yes
  7. 7.Can a triangle have sides of 11 cm, 3 cm and 3 cm? (a) Yes (b) No
  8. 8.In an isosceles triangle, the two equal angles are 66° each. What is the third angle (in degrees)?
  9. 9.In a right-angled triangle, one of the other two angles is 19°. What is the third angle (in degrees)?
  10. 10.In a right-angled triangle, one of the other two angles is 20°. What is the third angle (in degrees)?
  11. 11.In triangle ABC, angle A = 70° and angle B = 77°. What is angle C (in degrees)?
  12. 12.The two shorter sides of a right-angled triangle are 18 cm and 24 cm. How long is the longest side (in cm)?
  13. 13.In a right-angled triangle, one of the other two angles is 30°. What is the third angle (in degrees)?
  14. 14.In an isosceles triangle, the angle between the two equal sides is 54°. What is each of the other two angles (in degrees)?
  15. 15.In a right-angled triangle, one of the other two angles is 65°. What is the third angle (in degrees)?
  16. 16.Can a triangle have sides of 21 cm, 5 cm and 12 cm? (a) No (b) Yes
  17. 17.In triangle ABC, angle A = 85° and angle B = 46°. What is angle C (in degrees)?
  18. 18.In an isosceles triangle, the angle between the two equal sides is 140°. What is each of the other two angles (in degrees)?
  19. 19.In triangle ABC, angle A = 45° and angle B = 27°. What is angle C (in degrees)?
  20. 20.In triangle ABC, angle A = 26° and angle B = 123°. What is angle C (in degrees)?
  21. 21.In an isosceles triangle, the angle between the two equal sides is 100°. What is each of the other two angles (in degrees)?
  22. 22.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)?
  23. 23.Can a triangle have sides of 12 cm, 7 cm and 19 cm? (a) No (b) Yes
  24. 24.In triangle ABC, angle A = 26° and angle B = 102°. What is angle C (in degrees)?
  25. 25.Can a triangle have sides of 6 cm, 11 cm and 4 cm? (a) Yes (b) No
  26. 26.Can a triangle have sides of 4 cm, 2 cm and 9 cm? (a) Yes (b) No
  27. 27.Can a triangle have sides of 11 cm, 23 cm and 8 cm? (a) Yes (b) No
  28. 28.Can a triangle have sides of 8 cm, 6 cm and 4 cm? (a) No (b) Yes
  29. 29.The angles of a triangle are in the ratio 2 : 7 : 9. What is the biggest angle (in degrees)?
  30. 30.In an isosceles triangle, the angle between the two equal sides is 76°. What is each of the other two angles (in degrees)?
  31. 31.Can a triangle have sides of 10 cm, 3 cm and 2 cm? (a) Yes (b) No
  32. 32.In triangle ABC, angle A = 70° and angle B = 27°. What is angle C (in degrees)?
  33. 33.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  34. 34.An exterior angle of a triangle is 107°. One of its two interior opposite angles is 72°. What is the other one (in degrees)?
  35. 35.In triangle ABC, angle A = 82° and angle B = 46°. What is angle C (in degrees)?
  36. 36.In triangle ABC, angle A = 93° and angle B = 55°. What is angle C (in degrees)?
  37. 37.Can a triangle have sides of 14 cm, 6 cm and 4 cm? (a) No (b) Yes
  38. 38.In triangle ABC, angle A = 71° and angle B = 45°. What is angle C (in degrees)?
  39. 39.The two interior opposite angles of a triangle are 60° and 52°. What is the exterior angle (in degrees)?
  40. 40.An exterior angle of a triangle is 71°. One of its two interior opposite angles is 23°. What is the other one (in degrees)?

Answer key

  1. 18
  2. 8
  3. 81
  4. No
  5. 84
  6. Yes
  7. No
  8. 48
  9. 71
  10. 70
  11. 33
  12. 30
  13. 60
  14. 63
  15. 25
  16. No
  17. 49
  18. 20
  19. 108
  20. 31
  21. 40
  22. 24
  23. No
  24. 52
  25. No
  26. No
  27. No
  28. Yes
  29. 90
  30. 52
  31. No
  32. 83
  33. 75
  34. 35
  35. 52
  36. 32
  37. No
  38. 64
  39. 112
  40. 48

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