← 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 869 · 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 : 1 : 2. What is the smallest angle (in degrees)?
  2. 2.In triangle ABC, angle A = 73° and angle B = 26°. What is angle C (in degrees)?
  3. 3.The angles of a triangle are in the ratio 2 : 7 : 9. What is the biggest angle (in degrees)?
  4. 4.In a right-angled triangle, one of the other two angles is 30°. What is the third angle (in degrees)?
  5. 5.In triangle ABC, angle A = 50° and angle B = 64°. What is angle C (in degrees)?
  6. 6.In a right-angled triangle, one of the other two angles is 44°. What is the third angle (in degrees)?
  7. 7.The two interior opposite angles of a triangle are 73° and 23°. What is the exterior angle (in degrees)?
  8. 8.The two interior opposite angles of a triangle are 28° and 47°. What is the exterior angle (in degrees)?
  9. 9.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  10. 10.In triangle ABC, angle A = 54° and angle B = 48°. What is angle C (in degrees)?
  11. 11.In a right-angled triangle, one of the other two angles is 60°. What is the third angle (in degrees)?
  12. 12.In an isosceles triangle, the angle between the two equal sides is 142°. What is each of the other two angles (in degrees)?
  13. 13.In triangle ABC, angle A = 80° and angle B = 20°. What is angle C (in degrees)?
  14. 14.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  15. 15.In an isosceles triangle, the two equal angles are 27° each. What is the third angle (in degrees)?
  16. 16.In triangle ABC, angle A = 62° and angle B = 37°. What is angle C (in degrees)?
  17. 17.An exterior angle of a triangle is 120°. One of its two interior opposite angles is 68°. What is the other one (in degrees)?
  18. 18.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  19. 19.Can a triangle have sides of 4 cm, 11 cm and 12 cm? (a) Yes (b) No
  20. 20.In a right-angled triangle, one of the other two angles is 19°. What is the third angle (in degrees)?
  21. 21.In triangle ABC, angle A = 34° and angle B = 63°. What is angle C (in degrees)?
  22. 22.In triangle ABC, angle A = 51° and angle B = 39°. What is angle C (in degrees)?
  23. 23.In a right-angled triangle, one of the other two angles is 68°. What is the third angle (in degrees)?
  24. 24.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)?
  25. 25.In triangle ABC, angle A = 23° and angle B = 116°. What is angle C (in degrees)?
  26. 26.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)?
  27. 27.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  28. 28.In triangle ABC, angle A = 62° and angle B = 84°. What is angle C (in degrees)?
  29. 29.Can a triangle have sides of 3 cm, 13 cm and 6 cm? (a) No (b) Yes
  30. 30.The two interior opposite angles of a triangle are 22° and 55°. What is the exterior angle (in degrees)?
  31. 31.The longest side of a right-angled triangle is 25 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  32. 32.In triangle ABC, angle A = 72° and angle B = 25°. What is angle C (in degrees)?
  33. 33.The two shorter sides of a right-angled triangle are 6 cm and 8 cm. How long is the longest side (in cm)?
  34. 34.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  35. 35.In a right-angled triangle, one of the other two angles is 20°. What is the third angle (in degrees)?
  36. 36.Can a triangle have sides of 9 cm, 9 cm and 11 cm? (a) Yes (b) No
  37. 37.The two interior opposite angles of a triangle are 28° and 49°. What is the exterior angle (in degrees)?
  38. 38.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  39. 39.In an isosceles triangle, the two equal angles are 53° each. What is the third angle (in degrees)?
  40. 40.An exterior angle of a triangle is 99°. One of its two interior opposite angles is 58°. What is the other one (in degrees)?

Answer key

  1. 45
  2. 81
  3. 90
  4. 60
  5. 66
  6. 46
  7. 96
  8. 75
  9. 17
  10. 78
  11. 30
  12. 19
  13. 80
  14. 25
  15. 126
  16. 81
  17. 52
  18. 72
  19. Yes
  20. 71
  21. 83
  22. 90
  23. 22
  24. 12
  25. 41
  26. 10
  27. 80
  28. 34
  29. No
  30. 77
  31. 20
  32. 83
  33. 10
  34. 20
  35. 70
  36. Yes
  37. 77
  38. 120
  39. 74
  40. 41

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