← 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 831 · 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 5 cm and one of the other sides is 4 cm. How long is the third side (in cm)?
  2. 2.In triangle ABC, angle A = 56° and angle B = 76°. What is angle C (in degrees)?
  3. 3.In triangle ABC, angle A = 97° and angle B = 43°. What is angle C (in degrees)?
  4. 4.Can a triangle have sides of 11 cm, 13 cm and 3 cm? (a) Yes (b) No
  5. 5.Can a triangle have sides of 7 cm, 11 cm and 7 cm? (a) Yes (b) No
  6. 6.Can a triangle have sides of 10 cm, 9 cm and 12 cm? (a) Yes (b) No
  7. 7.In a right-angled triangle, one of the other two angles is 74°. What is the third angle (in degrees)?
  8. 8.In triangle ABC, angle A = 38° and angle B = 64°. What is angle C (in degrees)?
  9. 9.An exterior angle of a triangle is 91°. One of its two interior opposite angles is 70°. What is the other one (in degrees)?
  10. 10.Can a triangle have sides of 4 cm, 6 cm and 5 cm? (a) Yes (b) No
  11. 11.In triangle ABC, angle A = 71° and angle B = 28°. What is angle C (in degrees)?
  12. 12.In an isosceles triangle, the two equal angles are 30° each. What is the third angle (in degrees)?
  13. 13.Can a triangle have sides of 6 cm, 4 cm and 8 cm? (a) No (b) Yes
  14. 14.In triangle ABC, angle A = 42° and angle B = 113°. What is angle C (in degrees)?
  15. 15.The two interior opposite angles of a triangle are 54° and 78°. What is the exterior angle (in degrees)?
  16. 16.In an isosceles triangle, the two equal angles are 73° each. What is the third angle (in degrees)?
  17. 17.The two shorter sides of a right-angled triangle are 12 cm and 5 cm. How long is the longest side (in cm)?
  18. 18.In triangle ABC, angle A = 46° and angle B = 80°. What is angle C (in degrees)?
  19. 19.In triangle ABC, angle A = 53° and angle B = 20°. What is angle C (in degrees)?
  20. 20.In triangle ABC, angle A = 56° and angle B = 38°. What is angle C (in degrees)?
  21. 21.The angles of a triangle are in the ratio 1 : 1 : 2. What is the smallest angle (in degrees)?
  22. 22.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)?
  23. 23.The two shorter sides of a right-angled triangle are 9 cm and 12 cm. How long is the longest side (in cm)?
  24. 24.In a right-angled triangle, one of the other two angles is 26°. What is the third angle (in degrees)?
  25. 25.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  26. 26.The two shorter sides of a right-angled triangle are 36 cm and 15 cm. How long is the longest side (in cm)?
  27. 27.In triangle ABC, angle A = 51° and angle B = 106°. What is angle C (in degrees)?
  28. 28.In an isosceles triangle, the two equal angles are 32° each. What is the third angle (in degrees)?
  29. 29.An exterior angle of a triangle is 131°. One of its two interior opposite angles is 55°. What is the other one (in degrees)?
  30. 30.In triangle ABC, angle A = 67° and angle B = 72°. What is angle C (in degrees)?
  31. 31.In an isosceles triangle, the two equal angles are 76° each. What is the third angle (in degrees)?
  32. 32.An exterior angle of a triangle is 100°. One of its two interior opposite angles is 22°. What is the other one (in degrees)?
  33. 33.The two interior opposite angles of a triangle are 74° and 23°. What is the exterior angle (in degrees)?
  34. 34.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  35. 35.In a right-angled triangle, one of the other two angles is 13°. What is the third angle (in degrees)?
  36. 36.Can a triangle have sides of 7 cm, 7 cm and 5 cm? (a) Yes (b) No
  37. 37.The angles of a triangle are in the ratio 5 : 6 : 7. What is the biggest angle (in degrees)?
  38. 38.Can a triangle have sides of 17 cm, 12 cm and 5 cm? (a) Yes (b) No
  39. 39.Can a triangle have sides of 2 cm, 5 cm and 5 cm? (a) No (b) Yes
  40. 40.In a right-angled triangle, one of the other two angles is 32°. What is the third angle (in degrees)?

Answer key

  1. 3
  2. 48
  3. 40
  4. Yes
  5. Yes
  6. Yes
  7. 16
  8. 78
  9. 21
  10. Yes
  11. 81
  12. 120
  13. Yes
  14. 25
  15. 132
  16. 34
  17. 13
  18. 54
  19. 107
  20. 86
  21. 45
  22. 24
  23. 15
  24. 64
  25. 17
  26. 39
  27. 23
  28. 116
  29. 76
  30. 41
  31. 28
  32. 78
  33. 97
  34. 80
  35. 77
  36. Yes
  37. 70
  38. No
  39. Yes
  40. 58

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