← 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 833 · 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 17 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  2. 2.In a right-angled triangle, one of the other two angles is 79°. What is the third angle (in degrees)?
  3. 3.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  4. 4.An exterior angle of a triangle is 75°. One of its two interior opposite angles is 45°. What is the other one (in degrees)?
  5. 5.In a right-angled triangle, one of the other two angles is 25°. What is the third angle (in degrees)?
  6. 6.An exterior angle of a triangle is 63°. One of its two interior opposite angles is 34°. What is the other one (in degrees)?
  7. 7.In an isosceles triangle, the two equal angles are 39° each. What is the third angle (in degrees)?
  8. 8.Can a triangle have sides of 6 cm, 10 cm and 16 cm? (a) No (b) Yes
  9. 9.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?
  10. 10.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  11. 11.In triangle ABC, angle A = 34° and angle B = 28°. What is angle C (in degrees)?
  12. 12.In an isosceles triangle, the angle between the two equal sides is 46°. What is each of the other two angles (in degrees)?
  13. 13.In a right-angled triangle, one of the other two angles is 40°. What is the third angle (in degrees)?
  14. 14.In an isosceles triangle, the angle between the two equal sides is 102°. What is each of the other two angles (in degrees)?
  15. 15.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  16. 16.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  17. 17.In an isosceles triangle, the angle between the two equal sides is 100°. What is each of the other two angles (in degrees)?
  18. 18.In triangle ABC, angle A = 87° and angle B = 28°. What is angle C (in degrees)?
  19. 19.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  20. 20.The two interior opposite angles of a triangle are 35° and 67°. What is the exterior angle (in degrees)?
  21. 21.Can a triangle have sides of 8 cm, 13 cm and 2 cm? (a) No (b) Yes
  22. 22.The longest side of a right-angled triangle is 15 cm and one of the other sides is 9 cm. How long is the third side (in cm)?
  23. 23.In an isosceles triangle, the angle between the two equal sides is 92°. What is each of the other two angles (in degrees)?
  24. 24.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)?
  25. 25.The longest side of a right-angled triangle is 10 cm and one of the other sides is 6 cm. How long is the third side (in cm)?
  26. 26.In triangle ABC, angle A = 67° and angle B = 45°. What is angle C (in degrees)?
  27. 27.In triangle ABC, angle A = 56° and angle B = 43°. What is angle C (in degrees)?
  28. 28.The two interior opposite angles of a triangle are 24° and 53°. What is the exterior angle (in degrees)?
  29. 29.The angles of a triangle are in the ratio 1 : 2 : 6. What is the smallest angle (in degrees)?
  30. 30.In a right-angled triangle, one of the other two angles is 52°. What is the third angle (in degrees)?
  31. 31.The two interior opposite angles of a triangle are 76° and 77°. What is the exterior angle (in degrees)?
  32. 32.In triangle ABC, angle A = 66° and angle B = 35°. What is angle C (in degrees)?
  33. 33.In a right-angled triangle, one of the other two angles is 38°. What is the third angle (in degrees)?
  34. 34.In triangle ABC, angle A = 70° and angle B = 79°. What is angle C (in degrees)?
  35. 35.In triangle ABC, angle A = 42° and angle B = 39°. What is angle C (in degrees)?
  36. 36.In an isosceles triangle, the two equal angles are 40° each. What is the third angle (in degrees)?
  37. 37.In a right-angled triangle, one of the other two angles is 67°. What is the third angle (in degrees)?
  38. 38.In triangle ABC, angle A = 57° and angle B = 100°. What is angle C (in degrees)?
  39. 39.In an isosceles triangle, the two equal angles are 80° each. What is the third angle (in degrees)?
  40. 40.The angles of a triangle are in the ratio 1 : 2 : 2. What is the smallest angle (in degrees)?

Answer key

  1. 8
  2. 11
  3. 72
  4. 30
  5. 65
  6. 29
  7. 102
  8. No
  9. 50
  10. 40
  11. 118
  12. 67
  13. 50
  14. 39
  15. 20
  16. 20
  17. 40
  18. 65
  19. 17
  20. 102
  21. No
  22. 12
  23. 44
  24. 10
  25. 8
  26. 68
  27. 81
  28. 77
  29. 20
  30. 38
  31. 153
  32. 79
  33. 52
  34. 31
  35. 99
  36. 100
  37. 23
  38. 23
  39. 20
  40. 36

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