← 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 575 · 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.An exterior angle of a triangle is 86°. One of its two interior opposite angles is 37°. What is the other one (in degrees)?
  2. 2.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  3. 3.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)?
  4. 4.In an isosceles triangle, the angle between the two equal sides is 126°. What is each of the other two angles (in degrees)?
  5. 5.Can a triangle have sides of 13 cm, 3 cm and 12 cm? (a) Yes (b) No
  6. 6.In a right-angled triangle, one of the other two angles is 30°. What is the third angle (in degrees)?
  7. 7.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)?
  8. 8.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)?
  9. 9.Can a triangle have sides of 12 cm, 10 cm and 7 cm? (a) No (b) Yes
  10. 10.In an isosceles triangle, the two equal angles are 30° each. What is the third angle (in degrees)?
  11. 11.The two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  12. 12.In triangle ABC, angle A = 25° and angle B = 40°. What is angle C (in degrees)?
  13. 13.In an isosceles triangle, the angle between the two equal sides is 48°. What is each of the other two angles (in degrees)?
  14. 14.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  15. 15.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?
  16. 16.Can a triangle have sides of 3 cm, 10 cm and 2 cm? (a) No (b) Yes
  17. 17.In triangle ABC, angle A = 28° and angle B = 113°. What is angle C (in degrees)?
  18. 18.Can a triangle have sides of 6 cm, 9 cm and 19 cm? (a) Yes (b) No
  19. 19.In a right-angled triangle, one of the other two angles is 70°. What is the third angle (in degrees)?
  20. 20.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  21. 21.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  22. 22.In triangle ABC, angle A = 92° and angle B = 34°. What is angle C (in degrees)?
  23. 23.Can a triangle have sides of 23 cm, 10 cm and 10 cm? (a) No (b) Yes
  24. 24.In a right-angled triangle, one of the other two angles is 44°. What is the third angle (in degrees)?
  25. 25.In a right-angled triangle, one of the other two angles is 37°. What is the third angle (in degrees)?
  26. 26.The angles of a triangle are in the ratio 5 : 6 : 7. What is the biggest angle (in degrees)?
  27. 27.In an isosceles triangle, the two equal angles are 64° each. What is the third angle (in degrees)?
  28. 28.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  29. 29.In triangle ABC, angle A = 53° and angle B = 66°. What is angle C (in degrees)?
  30. 30.In a right-angled triangle, one of the other two angles is 36°. What is the third angle (in degrees)?
  31. 31.The two interior opposite angles of a triangle are 68° and 54°. What is the exterior angle (in degrees)?
  32. 32.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?
  33. 33.Can a triangle have sides of 7 cm, 10 cm and 21 cm? (a) Yes (b) No
  34. 34.Can a triangle have sides of 10 cm, 20 cm and 10 cm? (a) No (b) Yes
  35. 35.In a right-angled triangle, one of the other two angles is 74°. What is the third angle (in degrees)?
  36. 36.The two interior opposite angles of a triangle are 28° and 65°. What is the exterior angle (in degrees)?
  37. 37.In an isosceles triangle, the angle between the two equal sides is 44°. What is each of the other two angles (in degrees)?
  38. 38.The longest side of a right-angled triangle is 25 cm and one of the other sides is 24 cm. How long is the third side (in cm)?
  39. 39.In triangle ABC, angle A = 22° and angle B = 104°. What is angle C (in degrees)?
  40. 40.In an isosceles triangle, the angle between the two equal sides is 124°. What is each of the other two angles (in degrees)?

Answer key

  1. 49
  2. 90
  3. 12
  4. 27
  5. Yes
  6. 60
  7. 15
  8. 36
  9. Yes
  10. 120
  11. 39
  12. 115
  13. 66
  14. 72
  15. 50
  16. No
  17. 39
  18. No
  19. 20
  20. 100
  21. 25
  22. 54
  23. No
  24. 46
  25. 53
  26. 70
  27. 52
  28. 17
  29. 61
  30. 54
  31. 122
  32. 48
  33. No
  34. No
  35. 16
  36. 93
  37. 68
  38. 7
  39. 54
  40. 28

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