← 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 666 · 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.The longest side of a right-angled triangle is 25 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  2. 2.In an isosceles triangle, the two equal angles are 31° each. What is the third angle (in degrees)?
  3. 3.In triangle ABC, angle A = 45° and angle B = 46°. What is angle C (in degrees)?
  4. 4.In a right-angled triangle, one of the other two angles is 15°. What is the third angle (in degrees)?
  5. 5.Can a triangle have sides of 7 cm, 7 cm and 5 cm? (a) No (b) Yes
  6. 6.An exterior angle of a triangle is 84°. One of its two interior opposite angles is 55°. What is the other one (in degrees)?
  7. 7.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  8. 8.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  9. 9.In triangle ABC, angle A = 67° and angle B = 83°. What is angle C (in degrees)?
  10. 10.The angles of a triangle are in the ratio 2 : 2 : 5. What is the smallest angle (in degrees)?
  11. 11.The two interior opposite angles of a triangle are 29° and 41°. What is the exterior angle (in degrees)?
  12. 12.In a right-angled triangle, one of the other two angles is 49°. What is the third angle (in degrees)?
  13. 13.Can a triangle have sides of 2 cm, 7 cm and 2 cm? (a) No (b) Yes
  14. 14.Can a triangle have sides of 8 cm, 23 cm and 10 cm? (a) Yes (b) No
  15. 15.In a right-angled triangle, one of the other two angles is 76°. What is the third angle (in degrees)?
  16. 16.The two interior opposite angles of a triangle are 53° and 62°. What is the exterior angle (in degrees)?
  17. 17.Can a triangle have sides of 10 cm, 10 cm and 2 cm? (a) Yes (b) No
  18. 18.Can a triangle have sides of 9 cm, 9 cm and 7 cm? (a) No (b) Yes
  19. 19.An exterior angle of a triangle is 77°. One of its two interior opposite angles is 27°. What is the other one (in degrees)?
  20. 20.An exterior angle of a triangle is 71°. One of its two interior opposite angles is 46°. What is the other one (in degrees)?
  21. 21.In an isosceles triangle, the angle between the two equal sides is 50°. What is each of the other two angles (in degrees)?
  22. 22.In an isosceles triangle, the angle between the two equal sides is 46°. What is each of the other two angles (in degrees)?
  23. 23.In an isosceles triangle, the angle between the two equal sides is 30°. What is each of the other two angles (in degrees)?
  24. 24.In an isosceles triangle, the two equal angles are 60° each. What is the third angle (in degrees)?
  25. 25.The two interior opposite angles of a triangle are 55° and 54°. What is the exterior angle (in degrees)?
  26. 26.The two interior opposite angles of a triangle are 61° and 68°. What is the exterior angle (in degrees)?
  27. 27.In triangle ABC, angle A = 99° and angle B = 31°. What is angle C (in degrees)?
  28. 28.In a right-angled triangle, one of the other two angles is 21°. What is the third angle (in degrees)?
  29. 29.An exterior angle of a triangle is 141°. One of its two interior opposite angles is 62°. What is the other one (in degrees)?
  30. 30.The angles of a triangle are in the ratio 3 : 5 : 7. What is the biggest angle (in degrees)?
  31. 31.An exterior angle of a triangle is 104°. One of its two interior opposite angles is 75°. What is the other one (in degrees)?
  32. 32.The two shorter sides of a right-angled triangle are 12 cm and 16 cm. How long is the longest side (in cm)?
  33. 33.In triangle ABC, angle A = 48° and angle B = 102°. What is angle C (in degrees)?
  34. 34.In a right-angled triangle, one of the other two angles is 26°. What is the third angle (in degrees)?
  35. 35.An exterior angle of a triangle is 91°. One of its two interior opposite angles is 54°. What is the other one (in degrees)?
  36. 36.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  37. 37.In an isosceles triangle, the two equal angles are 25° each. What is the third angle (in degrees)?
  38. 38.In a right-angled triangle, one of the other two angles is 30°. What is the third angle (in degrees)?
  39. 39.Can a triangle have sides of 11 cm, 6 cm and 17 cm? (a) Yes (b) No
  40. 40.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)?

Answer key

  1. 20
  2. 118
  3. 89
  4. 75
  5. Yes
  6. 29
  7. 100
  8. 80
  9. 30
  10. 40
  11. 70
  12. 41
  13. No
  14. No
  15. 14
  16. 115
  17. Yes
  18. Yes
  19. 50
  20. 25
  21. 65
  22. 67
  23. 75
  24. 60
  25. 109
  26. 129
  27. 50
  28. 69
  29. 79
  30. 84
  31. 29
  32. 20
  33. 30
  34. 64
  35. 37
  36. 25
  37. 130
  38. 60
  39. No
  40. 12

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