← 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 857 · 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 triangle ABC, angle A = 28° and angle B = 95°. What is angle C (in degrees)?
  2. 2.In triangle ABC, angle A = 94° and angle B = 20°. What is angle C (in degrees)?
  3. 3.In an isosceles triangle, the angle between the two equal sides is 64°. What is each of the other two angles (in degrees)?
  4. 4.In triangle ABC, angle A = 41° and angle B = 63°. What is angle C (in degrees)?
  5. 5.In a right-angled triangle, one of the other two angles is 59°. What is the third angle (in degrees)?
  6. 6.In an isosceles triangle, the two equal angles are 75° each. What is the third angle (in degrees)?
  7. 7.The two interior opposite angles of a triangle are 62° and 25°. What is the exterior angle (in degrees)?
  8. 8.In triangle ABC, angle A = 89° and angle B = 66°. What is angle C (in degrees)?
  9. 9.In a right-angled triangle, one of the other two angles is 21°. What is the third angle (in degrees)?
  10. 10.Can a triangle have sides of 6 cm, 12 cm and 15 cm? (a) Yes (b) No
  11. 11.Can a triangle have sides of 16 cm, 10 cm and 5 cm? (a) No (b) Yes
  12. 12.In an isosceles triangle, the two equal angles are 44° each. What is the third angle (in degrees)?
  13. 13.The two shorter sides of a right-angled triangle are 12 cm and 16 cm. How long is the longest side (in cm)?
  14. 14.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)?
  15. 15.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  16. 16.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  17. 17.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  18. 18.In an isosceles triangle, the angle between the two equal sides is 158°. What is each of the other two angles (in degrees)?
  19. 19.An exterior angle of a triangle is 83°. One of its two interior opposite angles is 30°. What is the other one (in degrees)?
  20. 20.In triangle ABC, angle A = 60° and angle B = 22°. What is angle C (in degrees)?
  21. 21.Can a triangle have sides of 5 cm, 11 cm and 8 cm? (a) No (b) Yes
  22. 22.In an isosceles triangle, the angle between the two equal sides is 108°. What is each of the other two angles (in degrees)?
  23. 23.The longest side of a right-angled triangle is 17 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  24. 24.In triangle ABC, angle A = 56° and angle B = 30°. What is angle C (in degrees)?
  25. 25.In triangle ABC, angle A = 73° and angle B = 22°. What is angle C (in degrees)?
  26. 26.In triangle ABC, angle A = 71° and angle B = 84°. What is angle C (in degrees)?
  27. 27.The angles of a triangle are in the ratio 1 : 2 : 6. What is the smallest angle (in degrees)?
  28. 28.In an isosceles triangle, the two equal angles are 66° each. What is the third angle (in degrees)?
  29. 29.In a right-angled triangle, one of the other two angles is 60°. What is the third angle (in degrees)?
  30. 30.In triangle ABC, angle A = 20° and angle B = 123°. What is angle C (in degrees)?
  31. 31.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  32. 32.In an isosceles triangle, the two equal angles are 20° each. What is the third angle (in degrees)?
  33. 33.In a right-angled triangle, one of the other two angles is 41°. What is the third angle (in degrees)?
  34. 34.The angles of a triangle are in the ratio 2 : 7 : 9. What is the biggest angle (in degrees)?
  35. 35.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)?
  36. 36.In a right-angled triangle, one of the other two angles is 67°. What is the third angle (in degrees)?
  37. 37.In a right-angled triangle, one of the other two angles is 68°. What is the third angle (in degrees)?
  38. 38.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  39. 39.Can a triangle have sides of 4 cm, 11 cm and 6 cm? (a) Yes (b) No
  40. 40.The two shorter sides of a right-angled triangle are 12 cm and 5 cm. How long is the longest side (in cm)?

Answer key

  1. 57
  2. 66
  3. 58
  4. 76
  5. 31
  6. 30
  7. 87
  8. 25
  9. 69
  10. Yes
  11. No
  12. 92
  13. 20
  14. 12
  15. 120
  16. 20
  17. 90
  18. 11
  19. 53
  20. 98
  21. Yes
  22. 36
  23. 8
  24. 94
  25. 85
  26. 25
  27. 20
  28. 48
  29. 30
  30. 37
  31. 90
  32. 140
  33. 49
  34. 90
  35. 7
  36. 23
  37. 22
  38. 18
  39. No
  40. 13

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