← 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 329 · 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 30 cm and one of the other sides is 18 cm. How long is the third side (in cm)?
  2. 2.In triangle ABC, angle A = 38° and angle B = 66°. What is angle C (in degrees)?
  3. 3.The two interior opposite angles of a triangle are 38° and 56°. What is the exterior angle (in degrees)?
  4. 4.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  5. 5.In a right-angled triangle, one of the other two angles is 19°. What is the third angle (in degrees)?
  6. 6.In triangle ABC, angle A = 38° and angle B = 72°. What is angle C (in degrees)?
  7. 7.The longest side of a right-angled triangle is 26 cm and one of the other sides is 10 cm. How long is the third side (in cm)?
  8. 8.In an isosceles triangle, the two equal angles are 82° each. What is the third angle (in degrees)?
  9. 9.In triangle ABC, angle A = 68° and angle B = 90°. What is angle C (in degrees)?
  10. 10.In triangle ABC, angle A = 32° and angle B = 101°. What is angle C (in degrees)?
  11. 11.In triangle ABC, angle A = 64° and angle B = 43°. What is angle C (in degrees)?
  12. 12.In an isosceles triangle, the angle between the two equal sides is 112°. What is each of the other two angles (in degrees)?
  13. 13.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  14. 14.The two interior opposite angles of a triangle are 67° and 74°. What is the exterior angle (in degrees)?
  15. 15.In triangle ABC, angle A = 60° and angle B = 84°. What is angle C (in degrees)?
  16. 16.An exterior angle of a triangle is 123°. One of its two interior opposite angles is 44°. What is the other one (in degrees)?
  17. 17.Can a triangle have sides of 8 cm, 5 cm and 8 cm? (a) No (b) Yes
  18. 18.Can a triangle have sides of 9 cm, 21 cm and 10 cm? (a) Yes (b) No
  19. 19.In a right-angled triangle, one of the other two angles is 25°. What is the third angle (in degrees)?
  20. 20.An exterior angle of a triangle is 70°. One of its two interior opposite angles is 46°. What is the other one (in degrees)?
  21. 21.In triangle ABC, angle A = 56° and angle B = 70°. What is angle C (in degrees)?
  22. 22.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  23. 23.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)?
  24. 24.In triangle ABC, angle A = 20° and angle B = 38°. What is angle C (in degrees)?
  25. 25.Can a triangle have sides of 8 cm, 5 cm and 5 cm? (a) No (b) Yes
  26. 26.The two shorter sides of a right-angled triangle are 3 cm and 4 cm. How long is the longest side (in cm)?
  27. 27.The angles of a triangle are in the ratio 2 : 3 : 5. What is the smallest angle (in degrees)?
  28. 28.The angles of a triangle are in the ratio 1 : 2 : 3. What is the biggest angle (in degrees)?
  29. 29.In triangle ABC, angle A = 47° and angle B = 56°. What is angle C (in degrees)?
  30. 30.Can a triangle have sides of 4 cm, 4 cm and 9 cm? (a) Yes (b) No
  31. 31.In triangle ABC, angle A = 51° and angle B = 21°. What is angle C (in degrees)?
  32. 32.Can a triangle have sides of 12 cm, 15 cm and 10 cm? (a) No (b) Yes
  33. 33.In triangle ABC, angle A = 42° and angle B = 38°. What is angle C (in degrees)?
  34. 34.Can a triangle have sides of 7 cm, 7 cm and 12 cm? (a) No (b) Yes
  35. 35.In triangle ABC, angle A = 31° and angle B = 67°. What is angle C (in degrees)?
  36. 36.The two interior opposite angles of a triangle are 63° and 67°. What is the exterior angle (in degrees)?
  37. 37.Can a triangle have sides of 22 cm, 10 cm and 8 cm? (a) No (b) Yes
  38. 38.In an isosceles triangle, the two equal angles are 80° each. What is the third angle (in degrees)?
  39. 39.The two interior opposite angles of a triangle are 43° and 77°. What is the exterior angle (in degrees)?
  40. 40.The two shorter sides of a right-angled triangle are 10 cm and 24 cm. How long is the longest side (in cm)?

Answer key

  1. 24
  2. 76
  3. 94
  4. 25
  5. 71
  6. 70
  7. 24
  8. 16
  9. 22
  10. 47
  11. 73
  12. 34
  13. 90
  14. 141
  15. 36
  16. 79
  17. Yes
  18. No
  19. 65
  20. 24
  21. 54
  22. 120
  23. 36
  24. 122
  25. Yes
  26. 5
  27. 36
  28. 90
  29. 77
  30. No
  31. 108
  32. Yes
  33. 100
  34. Yes
  35. 82
  36. 130
  37. No
  38. 20
  39. 120
  40. 26

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