← 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 284 · 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 an isosceles triangle, the two equal angles are 67° each. What is the third angle (in degrees)?
  2. 2.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  3. 3.In triangle ABC, angle A = 66° and angle B = 35°. What is angle C (in degrees)?
  4. 4.Can a triangle have sides of 8 cm, 7 cm and 4 cm? (a) No (b) Yes
  5. 5.The angles of a triangle are in the ratio 1 : 2 : 3. What is the smallest angle (in degrees)?
  6. 6.Can a triangle have sides of 12 cm, 11 cm and 2 cm? (a) Yes (b) No
  7. 7.In triangle ABC, angle A = 41° and angle B = 27°. What is angle C (in degrees)?
  8. 8.In a right-angled triangle, one of the other two angles is 35°. What is the third angle (in degrees)?
  9. 9.In triangle ABC, angle A = 38° and angle B = 67°. What is angle C (in degrees)?
  10. 10.In triangle ABC, angle A = 28° and angle B = 64°. What is angle C (in degrees)?
  11. 11.The two shorter sides of a right-angled triangle are 3 cm and 4 cm. How long is the longest side (in cm)?
  12. 12.The angles of a triangle are in the ratio 1 : 2 : 3. What is the biggest angle (in degrees)?
  13. 13.The two interior opposite angles of a triangle are 38° and 63°. What is the exterior angle (in degrees)?
  14. 14.In a right-angled triangle, one of the other two angles is 46°. What is the third angle (in degrees)?
  15. 15.The longest side of a right-angled triangle is 17 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  16. 16.The two interior opposite angles of a triangle are 69° and 27°. What is the exterior angle (in degrees)?
  17. 17.In a right-angled triangle, one of the other two angles is 27°. What is the third angle (in degrees)?
  18. 18.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  19. 19.In an isosceles triangle, the angle between the two equal sides is 52°. What is each of the other two angles (in degrees)?
  20. 20.Can a triangle have sides of 8 cm, 9 cm and 13 cm? (a) No (b) Yes
  21. 21.The longest side of a right-angled triangle is 5 cm and one of the other sides is 3 cm. How long is the third side (in cm)?
  22. 22.In an isosceles triangle, the two equal angles are 85° each. What is the third angle (in degrees)?
  23. 23.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  24. 24.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)?
  25. 25.The angles of a triangle are in the ratio 2 : 3 : 5. What is the smallest angle (in degrees)?
  26. 26.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  27. 27.In a right-angled triangle, one of the other two angles is 63°. What is the third angle (in degrees)?
  28. 28.The angles of a triangle are in the ratio 1 : 1 : 2. What is the smallest angle (in degrees)?
  29. 29.In triangle ABC, angle A = 86° and angle B = 31°. What is angle C (in degrees)?
  30. 30.In an isosceles triangle, the two equal angles are 49° each. What is the third angle (in degrees)?
  31. 31.In triangle ABC, angle A = 48° and angle B = 28°. What is angle C (in degrees)?
  32. 32.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  33. 33.Can a triangle have sides of 6 cm, 10 cm and 12 cm? (a) Yes (b) No
  34. 34.The angles of a triangle are in the ratio 2 : 7 : 9. What is the biggest angle (in degrees)?
  35. 35.Can a triangle have sides of 12 cm, 9 cm and 4 cm? (a) No (b) Yes
  36. 36.In an isosceles triangle, the two equal angles are 28° each. What is the third angle (in degrees)?
  37. 37.Can a triangle have sides of 3 cm, 2 cm and 4 cm? (a) Yes (b) No
  38. 38.An exterior angle of a triangle is 92°. One of its two interior opposite angles is 27°. What is the other one (in degrees)?
  39. 39.In triangle ABC, angle A = 40° and angle B = 113°. What is angle C (in degrees)?
  40. 40.In triangle ABC, angle A = 94° and angle B = 31°. What is angle C (in degrees)?

Answer key

  1. 46
  2. 75
  3. 79
  4. Yes
  5. 30
  6. Yes
  7. 112
  8. 55
  9. 75
  10. 88
  11. 5
  12. 90
  13. 101
  14. 44
  15. 8
  16. 96
  17. 63
  18. 18
  19. 64
  20. Yes
  21. 4
  22. 10
  23. 120
  24. 24
  25. 36
  26. 40
  27. 27
  28. 45
  29. 63
  30. 82
  31. 104
  32. 25
  33. Yes
  34. 90
  35. Yes
  36. 124
  37. Yes
  38. 65
  39. 27
  40. 55

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