← 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 895 · 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.Can a triangle have sides of 5 cm, 2 cm and 2 cm? (a) Yes (b) No
  2. 2.In an isosceles triangle, the angle between the two equal sides is 36°. What is each of the other two angles (in degrees)?
  3. 3.In a right-angled triangle, one of the other two angles is 30°. What is the third angle (in degrees)?
  4. 4.The two interior opposite angles of a triangle are 38° and 35°. What is the exterior angle (in degrees)?
  5. 5.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  6. 6.The longest side of a right-angled triangle is 26 cm and one of the other sides is 24 cm. How long is the third side (in cm)?
  7. 7.In triangle ABC, angle A = 43° and angle B = 53°. What is angle C (in degrees)?
  8. 8.In an isosceles triangle, the two equal angles are 58° each. What is the third angle (in degrees)?
  9. 9.The two interior opposite angles of a triangle are 39° and 38°. What is the exterior angle (in degrees)?
  10. 10.In triangle ABC, angle A = 87° and angle B = 70°. What is angle C (in degrees)?
  11. 11.The two shorter sides of a right-angled triangle are 12 cm and 5 cm. How long is the longest side (in cm)?
  12. 12.In an isosceles triangle, the angle between the two equal sides is 64°. What is each of the other two angles (in degrees)?
  13. 13.In an isosceles triangle, the two equal angles are 53° each. What is the third angle (in degrees)?
  14. 14.In a right-angled triangle, one of the other two angles is 36°. What is the third angle (in degrees)?
  15. 15.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  16. 16.The two interior opposite angles of a triangle are 78° and 25°. What is the exterior angle (in degrees)?
  17. 17.In a right-angled triangle, one of the other two angles is 31°. What is the third angle (in degrees)?
  18. 18.In an isosceles triangle, the angle between the two equal sides is 26°. What is each of the other two angles (in degrees)?
  19. 19.In triangle ABC, angle A = 38° and angle B = 95°. What is angle C (in degrees)?
  20. 20.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  21. 21.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  22. 22.In a right-angled triangle, one of the other two angles is 71°. What is the third angle (in degrees)?
  23. 23.In an isosceles triangle, the angle between the two equal sides is 80°. What is each of the other two angles (in degrees)?
  24. 24.Can a triangle have sides of 5 cm, 5 cm and 8 cm? (a) Yes (b) No
  25. 25.In an isosceles triangle, the angle between the two equal sides is 140°. What is each of the other two angles (in degrees)?
  26. 26.An exterior angle of a triangle is 158°. One of its two interior opposite angles is 79°. What is the other one (in degrees)?
  27. 27.The two interior opposite angles of a triangle are 23° and 22°. What is the exterior angle (in degrees)?
  28. 28.An exterior angle of a triangle is 135°. One of its two interior opposite angles is 58°. What is the other one (in degrees)?
  29. 29.In triangle ABC, angle A = 85° and angle B = 61°. What is angle C (in degrees)?
  30. 30.In triangle ABC, angle A = 86° and angle B = 24°. What is angle C (in degrees)?
  31. 31.The longest side of a right-angled triangle is 13 cm and one of the other sides is 12 cm. How long is the third side (in cm)?
  32. 32.In an isosceles triangle, the two equal angles are 75° each. What is the third angle (in degrees)?
  33. 33.The two interior opposite angles of a triangle are 28° and 80°. What is the exterior angle (in degrees)?
  34. 34.In a right-angled triangle, one of the other two angles is 14°. What is the third angle (in degrees)?
  35. 35.An exterior angle of a triangle is 123°. One of its two interior opposite angles is 49°. What is the other one (in degrees)?
  36. 36.In triangle ABC, angle A = 88° and angle B = 63°. What is angle C (in degrees)?
  37. 37.Can a triangle have sides of 9 cm, 9 cm and 5 cm? (a) No (b) Yes
  38. 38.An exterior angle of a triangle is 126°. One of its two interior opposite angles is 69°. What is the other one (in degrees)?
  39. 39.In triangle ABC, angle A = 39° and angle B = 94°. What is angle C (in degrees)?
  40. 40.In an isosceles triangle, the two equal angles are 54° each. What is the third angle (in degrees)?

Answer key

  1. No
  2. 72
  3. 60
  4. 73
  5. 72
  6. 10
  7. 84
  8. 64
  9. 77
  10. 23
  11. 13
  12. 58
  13. 74
  14. 54
  15. 75
  16. 103
  17. 59
  18. 77
  19. 47
  20. 45
  21. 40
  22. 19
  23. 50
  24. Yes
  25. 20
  26. 79
  27. 45
  28. 77
  29. 34
  30. 70
  31. 5
  32. 30
  33. 108
  34. 76
  35. 74
  36. 29
  37. Yes
  38. 57
  39. 47
  40. 72

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