← 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 876 · 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 = 39° and angle B = 93°. What is angle C (in degrees)?
  2. 2.Can a triangle have sides of 24 cm, 11 cm and 8 cm? (a) No (b) Yes
  3. 3.In a right-angled triangle, one of the other two angles is 32°. What is the third angle (in degrees)?
  4. 4.In triangle ABC, angle A = 100° and angle B = 41°. What is angle C (in degrees)?
  5. 5.In an isosceles triangle, the two equal angles are 32° each. What is the third angle (in degrees)?
  6. 6.In triangle ABC, angle A = 75° and angle B = 57°. What is angle C (in degrees)?
  7. 7.The angles of a triangle are in the ratio 1 : 2 : 2. What is the smallest angle (in degrees)?
  8. 8.In a right-angled triangle, one of the other two angles is 38°. What is the third angle (in degrees)?
  9. 9.In triangle ABC, angle A = 22° and angle B = 40°. What is angle C (in degrees)?
  10. 10.The two interior opposite angles of a triangle are 39° and 40°. What is the exterior angle (in degrees)?
  11. 11.In an isosceles triangle, the two equal angles are 27° each. What is the third angle (in degrees)?
  12. 12.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  13. 13.In a right-angled triangle, one of the other two angles is 48°. What is the third angle (in degrees)?
  14. 14.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)?
  15. 15.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  16. 16.Can a triangle have sides of 11 cm, 8 cm and 20 cm? (a) Yes (b) No
  17. 17.In triangle ABC, angle A = 89° and angle B = 31°. What is angle C (in degrees)?
  18. 18.In a right-angled triangle, one of the other two angles is 58°. What is the third angle (in degrees)?
  19. 19.The two shorter sides of a right-angled triangle are 15 cm and 20 cm. How long is the longest side (in cm)?
  20. 20.In a right-angled triangle, one of the other two angles is 25°. What is the third angle (in degrees)?
  21. 21.An exterior angle of a triangle is 137°. One of its two interior opposite angles is 66°. What is the other one (in degrees)?
  22. 22.Can a triangle have sides of 15 cm, 4 cm and 9 cm? (a) No (b) Yes
  23. 23.Can a triangle have sides of 13 cm, 6 cm and 7 cm? (a) No (b) Yes
  24. 24.In an isosceles triangle, the angle between the two equal sides is 98°. What is each of the other two angles (in degrees)?
  25. 25.In triangle ABC, angle A = 90° and angle B = 27°. What is angle C (in degrees)?
  26. 26.Can a triangle have sides of 8 cm, 4 cm and 8 cm? (a) No (b) Yes
  27. 27.In triangle ABC, angle A = 26° and angle B = 116°. What is angle C (in degrees)?
  28. 28.An exterior angle of a triangle is 103°. One of its two interior opposite angles is 31°. What is the other one (in degrees)?
  29. 29.The two interior opposite angles of a triangle are 62° and 22°. What is the exterior angle (in degrees)?
  30. 30.In an isosceles triangle, the two equal angles are 71° each. What is the third angle (in degrees)?
  31. 31.An exterior angle of a triangle is 79°. One of its two interior opposite angles is 45°. What is the other one (in degrees)?
  32. 32.In an isosceles triangle, the angle between the two equal sides is 158°. What is each of the other two angles (in degrees)?
  33. 33.An exterior angle of a triangle is 123°. One of its two interior opposite angles is 79°. What is the other one (in degrees)?
  34. 34.In an isosceles triangle, the two equal angles are 77° each. What is the third angle (in degrees)?
  35. 35.Can a triangle have sides of 20 cm, 11 cm and 10 cm? (a) Yes (b) No
  36. 36.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  37. 37.Can a triangle have sides of 9 cm, 9 cm and 7 cm? (a) No (b) Yes
  38. 38.Can a triangle have sides of 8 cm, 21 cm and 11 cm? (a) Yes (b) No
  39. 39.An exterior angle of a triangle is 73°. One of its two interior opposite angles is 23°. What is the other one (in degrees)?
  40. 40.Can a triangle have sides of 13 cm, 3 cm and 10 cm? (a) No (b) Yes

Answer key

  1. 48
  2. No
  3. 58
  4. 39
  5. 116
  6. 48
  7. 36
  8. 52
  9. 118
  10. 79
  11. 126
  12. 90
  13. 42
  14. 15
  15. 90
  16. No
  17. 60
  18. 32
  19. 25
  20. 65
  21. 71
  22. No
  23. No
  24. 41
  25. 63
  26. Yes
  27. 38
  28. 72
  29. 84
  30. 38
  31. 34
  32. 11
  33. 44
  34. 26
  35. Yes
  36. 120
  37. Yes
  38. No
  39. 50
  40. No

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