← 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 32 · 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 an isosceles triangle, the angle between the two equal sides is 92°. What is each of the other two angles (in degrees)?
  2. 2.In a right-angled triangle, one of the other two angles is 41°. What is the third angle (in degrees)?
  3. 3.In an isosceles triangle, the two equal angles are 65° each. What is the third angle (in degrees)?
  4. 4.The two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  5. 5.In a right-angled triangle, one of the other two angles is 45°. What is the third angle (in degrees)?
  6. 6.In an isosceles triangle, the angle between the two equal sides is 24°. What is each of the other two angles (in degrees)?
  7. 7.In a right-angled triangle, one of the other two angles is 79°. What is the third angle (in degrees)?
  8. 8.The two shorter sides of a right-angled triangle are 24 cm and 18 cm. How long is the longest side (in cm)?
  9. 9.In a right-angled triangle, one of the other two angles is 21°. What is the third angle (in degrees)?
  10. 10.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  11. 11.An exterior angle of a triangle is 54°. One of its two interior opposite angles is 27°. What is the other one (in degrees)?
  12. 12.In an isosceles triangle, the angle between the two equal sides is 126°. What is each of the other two angles (in degrees)?
  13. 13.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  14. 14.In triangle ABC, angle A = 35° and angle B = 101°. What is angle C (in degrees)?
  15. 15.In a right-angled triangle, one of the other two angles is 33°. What is the third angle (in degrees)?
  16. 16.Can a triangle have sides of 13 cm, 5 cm and 5 cm? (a) No (b) Yes
  17. 17.An exterior angle of a triangle is 51°. One of its two interior opposite angles is 25°. What is the other one (in degrees)?
  18. 18.The two interior opposite angles of a triangle are 29° and 58°. What is the exterior angle (in degrees)?
  19. 19.In triangle ABC, angle A = 24° and angle B = 104°. What is angle C (in degrees)?
  20. 20.In triangle ABC, angle A = 56° and angle B = 51°. What is angle C (in degrees)?
  21. 21.Can a triangle have sides of 11 cm, 21 cm and 8 cm? (a) No (b) Yes
  22. 22.In triangle ABC, angle A = 20° and angle B = 137°. What is angle C (in degrees)?
  23. 23.Can a triangle have sides of 9 cm, 3 cm and 8 cm? (a) Yes (b) No
  24. 24.Can a triangle have sides of 7 cm, 7 cm and 7 cm? (a) Yes (b) No
  25. 25.In an isosceles triangle, the two equal angles are 46° each. What is the third angle (in degrees)?
  26. 26.In an isosceles triangle, the angle between the two equal sides is 84°. What is each of the other two angles (in degrees)?
  27. 27.In triangle ABC, angle A = 81° and angle B = 52°. What is angle C (in degrees)?
  28. 28.In an isosceles triangle, the two equal angles are 76° each. What is the third angle (in degrees)?
  29. 29.The longest side of a right-angled triangle is 5 cm and one of the other sides is 3 cm. How long is the third side (in cm)?
  30. 30.In an isosceles triangle, the two equal angles are 66° each. What is the third angle (in degrees)?
  31. 31.In triangle ABC, angle A = 20° and angle B = 99°. What is angle C (in degrees)?
  32. 32.In an isosceles triangle, the angle between the two equal sides is 124°. What is each of the other two angles (in degrees)?
  33. 33.In an isosceles triangle, the two equal angles are 80° each. What is the third angle (in degrees)?
  34. 34.Can a triangle have sides of 9 cm, 13 cm and 9 cm? (a) Yes (b) No
  35. 35.In triangle ABC, angle A = 72° and angle B = 26°. What is angle C (in degrees)?
  36. 36.In triangle ABC, angle A = 81° and angle B = 34°. What is angle C (in degrees)?
  37. 37.In a right-angled triangle, one of the other two angles is 23°. What is the third angle (in degrees)?
  38. 38.The two shorter sides of a right-angled triangle are 24 cm and 10 cm. How long is the longest side (in cm)?
  39. 39.In triangle ABC, angle A = 21° and angle B = 71°. What is angle C (in degrees)?
  40. 40.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)?

Answer key

  1. 44
  2. 49
  3. 50
  4. 39
  5. 45
  6. 78
  7. 11
  8. 30
  9. 69
  10. 90
  11. 27
  12. 27
  13. 75
  14. 44
  15. 57
  16. No
  17. 26
  18. 87
  19. 52
  20. 73
  21. No
  22. 23
  23. Yes
  24. Yes
  25. 88
  26. 48
  27. 47
  28. 28
  29. 4
  30. 48
  31. 61
  32. 28
  33. 20
  34. Yes
  35. 82
  36. 65
  37. 67
  38. 26
  39. 88
  40. 15

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