← 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 449 · 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 a right-angled triangle, one of the other two angles is 55°. What is the third angle (in degrees)?
  2. 2.The two interior opposite angles of a triangle are 36° and 35°. What is the exterior angle (in degrees)?
  3. 3.In triangle ABC, angle A = 21° and angle B = 108°. What is angle C (in degrees)?
  4. 4.In a right-angled triangle, one of the other two angles is 73°. What is the third angle (in degrees)?
  5. 5.In a right-angled triangle, one of the other two angles is 74°. What is the third angle (in degrees)?
  6. 6.The two interior opposite angles of a triangle are 72° and 61°. What is the exterior angle (in degrees)?
  7. 7.In an isosceles triangle, the angle between the two equal sides is 136°. What is each of the other two angles (in degrees)?
  8. 8.In a right-angled triangle, one of the other two angles is 56°. What is the third angle (in degrees)?
  9. 9.In a right-angled triangle, one of the other two angles is 76°. What is the third angle (in degrees)?
  10. 10.In an isosceles triangle, the angle between the two equal sides is 38°. What is each of the other two angles (in degrees)?
  11. 11.In an isosceles triangle, the angle between the two equal sides is 28°. What is each of the other two angles (in degrees)?
  12. 12.Can a triangle have sides of 2 cm, 2 cm and 3 cm? (a) Yes (b) No
  13. 13.In a right-angled triangle, one of the other two angles is 18°. What is the third angle (in degrees)?
  14. 14.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  15. 15.The angles of a triangle are in the ratio 1 : 2 : 3. What is the smallest angle (in degrees)?
  16. 16.Can a triangle have sides of 4 cm, 6 cm and 2 cm? (a) Yes (b) No
  17. 17.The two interior opposite angles of a triangle are 42° and 66°. What is the exterior angle (in degrees)?
  18. 18.In an isosceles triangle, the angle between the two equal sides is 108°. What is each of the other two angles (in degrees)?
  19. 19.In triangle ABC, angle A = 87° and angle B = 37°. What is angle C (in degrees)?
  20. 20.The longest side of a right-angled triangle is 15 cm and one of the other sides is 9 cm. How long is the third side (in cm)?
  21. 21.In an isosceles triangle, the angle between the two equal sides is 124°. What is each of the other two angles (in degrees)?
  22. 22.In triangle ABC, angle A = 74° and angle B = 60°. What is angle C (in degrees)?
  23. 23.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  24. 24.The angles of a triangle are in the ratio 2 : 3 : 5. What is the smallest angle (in degrees)?
  25. 25.In triangle ABC, angle A = 75° and angle B = 76°. What is angle C (in degrees)?
  26. 26.In triangle ABC, angle A = 56° and angle B = 68°. What is angle C (in degrees)?
  27. 27.Can a triangle have sides of 7 cm, 9 cm and 3 cm? (a) Yes (b) No
  28. 28.Can a triangle have sides of 11 cm, 20 cm and 4 cm? (a) No (b) Yes
  29. 29.Can a triangle have sides of 8 cm, 3 cm and 2 cm? (a) No (b) Yes
  30. 30.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  31. 31.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  32. 32.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  33. 33.In a right-angled triangle, one of the other two angles is 24°. What is the third angle (in degrees)?
  34. 34.In triangle ABC, angle A = 60° and angle B = 43°. What is angle C (in degrees)?
  35. 35.Can a triangle have sides of 9 cm, 12 cm and 2 cm? (a) Yes (b) No
  36. 36.The two interior opposite angles of a triangle are 63° and 28°. What is the exterior angle (in degrees)?
  37. 37.Can a triangle have sides of 12 cm, 11 cm and 7 cm? (a) No (b) Yes
  38. 38.In an isosceles triangle, the angle between the two equal sides is 82°. What is each of the other two angles (in degrees)?
  39. 39.In a right-angled triangle, one of the other two angles is 75°. What is the third angle (in degrees)?
  40. 40.In triangle ABC, angle A = 50° and angle B = 94°. What is angle C (in degrees)?

Answer key

  1. 35
  2. 71
  3. 51
  4. 17
  5. 16
  6. 133
  7. 22
  8. 34
  9. 14
  10. 71
  11. 76
  12. Yes
  13. 72
  14. 90
  15. 30
  16. No
  17. 108
  18. 36
  19. 56
  20. 12
  21. 28
  22. 46
  23. 25
  24. 36
  25. 29
  26. 56
  27. Yes
  28. No
  29. No
  30. 75
  31. 17
  32. 36
  33. 66
  34. 77
  35. No
  36. 91
  37. Yes
  38. 49
  39. 15
  40. 36

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