← 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 74 · 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 = 57° and angle B = 67°. What is angle C (in degrees)?
  2. 2.In triangle ABC, angle A = 56° and angle B = 38°. What is angle C (in degrees)?
  3. 3.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  4. 4.In triangle ABC, angle A = 21° and angle B = 75°. What is angle C (in degrees)?
  5. 5.In an isosceles triangle, the angle between the two equal sides is 72°. What is each of the other two angles (in degrees)?
  6. 6.The angles of a triangle are in the ratio 1 : 2 : 6. What is the smallest 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.In a right-angled triangle, one of the other two angles is 80°. What is the third angle (in degrees)?
  9. 9.The two interior opposite angles of a triangle are 77° and 56°. What is the exterior angle (in degrees)?
  10. 10.In a right-angled triangle, one of the other two angles is 40°. What is the third angle (in degrees)?
  11. 11.The two interior opposite angles of a triangle are 21° and 56°. What is the exterior angle (in degrees)?
  12. 12.Can a triangle have sides of 5 cm, 2 cm and 5 cm? (a) No (b) Yes
  13. 13.Can a triangle have sides of 20 cm, 10 cm and 11 cm? (a) Yes (b) No
  14. 14.In a right-angled triangle, one of the other two angles is 55°. What is the third angle (in degrees)?
  15. 15.In an isosceles triangle, the two equal angles are 53° each. What is the third angle (in degrees)?
  16. 16.An exterior angle of a triangle is 115°. One of its two interior opposite angles is 41°. What is the other one (in degrees)?
  17. 17.The two interior opposite angles of a triangle are 76° and 25°. What is the exterior angle (in degrees)?
  18. 18.An exterior angle of a triangle is 101°. One of its two interior opposite angles is 27°. What is the other one (in degrees)?
  19. 19.In triangle ABC, angle A = 38° and angle B = 47°. What is angle C (in degrees)?
  20. 20.Can a triangle have sides of 14 cm, 6 cm and 11 cm? (a) Yes (b) No
  21. 21.Can a triangle have sides of 9 cm, 3 cm and 14 cm? (a) Yes (b) No
  22. 22.The two shorter sides of a right-angled triangle are 10 cm and 24 cm. How long is the longest side (in cm)?
  23. 23.In triangle ABC, angle A = 66° and angle B = 43°. What is angle C (in degrees)?
  24. 24.Can a triangle have sides of 23 cm, 10 cm and 12 cm? (a) No (b) Yes
  25. 25.The two interior opposite angles of a triangle are 32° and 46°. What is the exterior angle (in degrees)?
  26. 26.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)?
  27. 27.In an isosceles triangle, the angle between the two equal sides is 124°. What is each of the other two angles (in degrees)?
  28. 28.In an isosceles triangle, the angle between the two equal sides is 130°. What is each of the other two angles (in degrees)?
  29. 29.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  30. 30.In triangle ABC, angle A = 42° and angle B = 88°. What is angle C (in degrees)?
  31. 31.Can a triangle have sides of 10 cm, 9 cm and 10 cm? (a) No (b) Yes
  32. 32.In an isosceles triangle, the angle between the two equal sides is 56°. What is each of the other two angles (in degrees)?
  33. 33.In triangle ABC, angle A = 44° and angle B = 48°. What is angle C (in degrees)?
  34. 34.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  35. 35.An exterior angle of a triangle is 55°. One of its two interior opposite angles is 34°. What is the other one (in degrees)?
  36. 36.An exterior angle of a triangle is 111°. One of its two interior opposite angles is 36°. What is the other one (in degrees)?
  37. 37.An exterior angle of a triangle is 52°. One of its two interior opposite angles is 27°. What is the other one (in degrees)?
  38. 38.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  39. 39.In a right-angled triangle, one of the other two angles is 23°. What is the third angle (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 16°. What is the third angle (in degrees)?

Answer key

  1. 56
  2. 86
  3. 17
  4. 84
  5. 54
  6. 20
  7. 15
  8. 10
  9. 133
  10. 50
  11. 77
  12. Yes
  13. Yes
  14. 35
  15. 74
  16. 74
  17. 101
  18. 74
  19. 95
  20. Yes
  21. No
  22. 26
  23. 71
  24. No
  25. 78
  26. 7
  27. 28
  28. 25
  29. 80
  30. 50
  31. Yes
  32. 62
  33. 88
  34. 90
  35. 21
  36. 75
  37. 25
  38. 100
  39. 67
  40. 74

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