← 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 311 · 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 13°. What is the third angle (in degrees)?
  2. 2.In triangle ABC, angle A = 64° and angle B = 80°. What is angle C (in degrees)?
  3. 3.In an isosceles triangle, the angle between the two equal sides is 20°. What is each of the other two angles (in degrees)?
  4. 4.Can a triangle have sides of 10 cm, 13 cm and 2 cm? (a) Yes (b) No
  5. 5.In triangle ABC, angle A = 54° and angle B = 39°. What is angle C (in degrees)?
  6. 6.Can a triangle have sides of 5 cm, 6 cm and 15 cm? (a) No (b) Yes
  7. 7.An exterior angle of a triangle is 61°. One of its two interior opposite angles is 40°. What is the other one (in degrees)?
  8. 8.In triangle ABC, angle A = 58° and angle B = 53°. What is angle C (in degrees)?
  9. 9.The angles of a triangle are in the ratio 1 : 2 : 2. What is the smallest angle (in degrees)?
  10. 10.In an isosceles triangle, the angle between the two equal sides is 76°. What is each of the other two angles (in degrees)?
  11. 11.Can a triangle have sides of 9 cm, 8 cm and 2 cm? (a) Yes (b) No
  12. 12.In triangle ABC, angle A = 38° and angle B = 41°. What is angle C (in degrees)?
  13. 13.In an isosceles triangle, the angle between the two equal sides is 30°. What is each of the other two angles (in degrees)?
  14. 14.The two shorter sides of a right-angled triangle are 4 cm and 3 cm. How long is the longest side (in cm)?
  15. 15.In triangle ABC, angle A = 20° and angle B = 77°. What is angle C (in degrees)?
  16. 16.The longest side of a right-angled triangle is 39 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  17. 17.Can a triangle have sides of 4 cm, 14 cm and 12 cm? (a) Yes (b) No
  18. 18.The two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  19. 19.In triangle ABC, angle A = 48° and angle B = 75°. What is angle C (in degrees)?
  20. 20.Can a triangle have sides of 23 cm, 9 cm and 11 cm? (a) No (b) Yes
  21. 21.The two shorter sides of a right-angled triangle are 24 cm and 10 cm. How long is the longest side (in cm)?
  22. 22.The longest side of a right-angled triangle is 5 cm and one of the other sides is 4 cm. How long is the third side (in cm)?
  23. 23.In triangle ABC, angle A = 61° and angle B = 21°. What is angle C (in degrees)?
  24. 24.In an isosceles triangle, the angle between the two equal sides is 70°. What is each of the other two angles (in degrees)?
  25. 25.Can a triangle have sides of 9 cm, 16 cm and 3 cm? (a) No (b) Yes
  26. 26.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  27. 27.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  28. 28.In triangle ABC, angle A = 44° and angle B = 45°. What is angle C (in degrees)?
  29. 29.The angles of a triangle are in the ratio 1 : 2 : 3. What is the biggest angle (in degrees)?
  30. 30.In triangle ABC, angle A = 73° and angle B = 51°. What is angle C (in degrees)?
  31. 31.An exterior angle of a triangle is 126°. One of its two interior opposite angles is 59°. What is the other one (in degrees)?
  32. 32.In triangle ABC, angle A = 32° and angle B = 104°. What is angle C (in degrees)?
  33. 33.An exterior angle of a triangle is 55°. One of its two interior opposite angles is 27°. What is the other one (in degrees)?
  34. 34.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  35. 35.In a right-angled triangle, one of the other two angles is 44°. What is the third angle (in degrees)?
  36. 36.In triangle ABC, angle A = 21° and angle B = 106°. What is angle C (in degrees)?
  37. 37.Can a triangle have sides of 8 cm, 11 cm and 8 cm? (a) Yes (b) No
  38. 38.In a right-angled triangle, one of the other two angles is 72°. What is the third angle (in degrees)?
  39. 39.Can a triangle have sides of 9 cm, 17 cm and 8 cm? (a) Yes (b) No
  40. 40.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?

Answer key

  1. 77
  2. 36
  3. 80
  4. No
  5. 87
  6. No
  7. 21
  8. 69
  9. 36
  10. 52
  11. Yes
  12. 101
  13. 75
  14. 5
  15. 83
  16. 36
  17. Yes
  18. 39
  19. 57
  20. No
  21. 26
  22. 3
  23. 98
  24. 55
  25. No
  26. 20
  27. 90
  28. 91
  29. 90
  30. 56
  31. 67
  32. 44
  33. 28
  34. 25
  35. 46
  36. 53
  37. Yes
  38. 18
  39. No
  40. 18

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