← 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 724 · 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 = 42° and angle B = 52°. What is angle C (in degrees)?
  2. 2.In an isosceles triangle, the angle between the two equal sides is 100°. What is each of the other two angles (in degrees)?
  3. 3.Can a triangle have sides of 7 cm, 9 cm and 7 cm? (a) Yes (b) No
  4. 4.In triangle ABC, angle A = 34° and angle B = 113°. What is angle C (in degrees)?
  5. 5.In a right-angled triangle, one of the other two angles is 46°. What is the third angle (in degrees)?
  6. 6.In an isosceles triangle, the angle between the two equal sides is 78°. What is each of the other two angles (in degrees)?
  7. 7.The two interior opposite angles of a triangle are 24° and 28°. What is the exterior angle (in degrees)?
  8. 8.In an isosceles triangle, the angle between the two equal sides is 34°. What is each of the other two angles (in degrees)?
  9. 9.In triangle ABC, angle A = 74° and angle B = 25°. What is angle C (in degrees)?
  10. 10.In an isosceles triangle, the angle between the two equal sides is 48°. What is each of the other two angles (in degrees)?
  11. 11.In triangle ABC, angle A = 24° and angle B = 45°. What is angle C (in degrees)?
  12. 12.Can a triangle have sides of 9 cm, 12 cm and 22 cm? (a) No (b) Yes
  13. 13.Can a triangle have sides of 10 cm, 11 cm and 22 cm? (a) Yes (b) No
  14. 14.The two shorter sides of a right-angled triangle are 16 cm and 12 cm. How long is the longest side (in cm)?
  15. 15.The longest side of a right-angled triangle is 39 cm and one of the other sides is 36 cm. How long is the third side (in cm)?
  16. 16.An exterior angle of a triangle is 104°. One of its two interior opposite angles is 80°. What is the other one (in degrees)?
  17. 17.In triangle ABC, angle A = 20° and angle B = 111°. What is angle C (in degrees)?
  18. 18.Can a triangle have sides of 17 cm, 8 cm and 5 cm? (a) Yes (b) No
  19. 19.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  20. 20.In a right-angled triangle, one of the other two angles is 80°. What is the third angle (in degrees)?
  21. 21.In triangle ABC, angle A = 81° and angle B = 44°. What is angle C (in degrees)?
  22. 22.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  23. 23.The two shorter sides of a right-angled triangle are 5 cm and 12 cm. How long is the longest side (in cm)?
  24. 24.In triangle ABC, angle A = 39° and angle B = 59°. What is angle C (in degrees)?
  25. 25.In an isosceles triangle, the angle between the two equal sides is 66°. What is each of the other two angles (in degrees)?
  26. 26.In a right-angled triangle, one of the other two angles is 37°. What is the third angle (in degrees)?
  27. 27.Can a triangle have sides of 4 cm, 4 cm and 2 cm? (a) No (b) Yes
  28. 28.The longest side of a right-angled triangle is 15 cm and one of the other sides is 12 cm. How long is the third side (in cm)?
  29. 29.Can a triangle have sides of 5 cm, 16 cm and 9 cm? (a) No (b) Yes
  30. 30.The angles of a triangle are in the ratio 2 : 3 : 5. What is the smallest angle (in degrees)?
  31. 31.Can a triangle have sides of 14 cm, 4 cm and 6 cm? (a) No (b) Yes
  32. 32.Can a triangle have sides of 13 cm, 5 cm and 4 cm? (a) No (b) Yes
  33. 33.In an isosceles triangle, the angle between the two equal sides is 54°. What is each of the other two angles (in degrees)?
  34. 34.The angles of a triangle are in the ratio 1 : 2 : 6. What is the smallest angle (in degrees)?
  35. 35.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  36. 36.An exterior angle of a triangle is 100°. One of its two interior opposite angles is 57°. What is the other one (in degrees)?
  37. 37.The longest side of a right-angled triangle is 25 cm and one of the other sides is 7 cm. How long is the third side (in cm)?
  38. 38.In a right-angled triangle, one of the other two angles is 39°. What is the third angle (in degrees)?
  39. 39.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  40. 40.An exterior angle of a triangle is 56°. One of its two interior opposite angles is 24°. What is the other one (in degrees)?

Answer key

  1. 86
  2. 40
  3. Yes
  4. 33
  5. 44
  6. 51
  7. 52
  8. 73
  9. 81
  10. 66
  11. 111
  12. No
  13. No
  14. 20
  15. 15
  16. 24
  17. 49
  18. No
  19. 75
  20. 10
  21. 55
  22. 17
  23. 13
  24. 82
  25. 57
  26. 53
  27. Yes
  28. 9
  29. No
  30. 36
  31. No
  32. No
  33. 63
  34. 20
  35. 25
  36. 43
  37. 24
  38. 51
  39. 17
  40. 32

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