← 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 838 · 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 two interior opposite angles of a triangle are 30° and 77°. What is the exterior angle (in degrees)?
  2. 2.In an isosceles triangle, the two equal angles are 21° each. What is the third angle (in degrees)?
  3. 3.The two interior opposite angles of a triangle are 31° and 63°. What is the exterior angle (in degrees)?
  4. 4.Can a triangle have sides of 11 cm, 5 cm and 9 cm? (a) No (b) Yes
  5. 5.An exterior angle of a triangle is 81°. One of its two interior opposite angles is 33°. What is the other one (in degrees)?
  6. 6.In an isosceles triangle, the two equal angles are 41° each. What is the third angle (in degrees)?
  7. 7.In a right-angled triangle, one of the other two angles is 36°. What is the third angle (in degrees)?
  8. 8.In triangle ABC, angle A = 84° and angle B = 63°. What is angle C (in degrees)?
  9. 9.In an isosceles triangle, the two equal angles are 66° each. What is the third angle (in degrees)?
  10. 10.An exterior angle of a triangle is 85°. One of its two interior opposite angles is 53°. What is the other one (in degrees)?
  11. 11.In an isosceles triangle, the two equal angles are 81° each. What is the third angle (in degrees)?
  12. 12.The two interior opposite angles of a triangle are 53° and 39°. What is the exterior angle (in degrees)?
  13. 13.In triangle ABC, angle A = 58° and angle B = 92°. What is angle C (in degrees)?
  14. 14.Can a triangle have sides of 7 cm, 7 cm and 14 cm? (a) No (b) Yes
  15. 15.The two interior opposite angles of a triangle are 58° and 35°. What is the exterior angle (in degrees)?
  16. 16.In a right-angled triangle, one of the other two angles is 29°. What is the third angle (in degrees)?
  17. 17.The longest side of a right-angled triangle is 25 cm and one of the other sides is 24 cm. How long is the third side (in cm)?
  18. 18.The two interior opposite angles of a triangle are 75° and 27°. What is the exterior angle (in degrees)?
  19. 19.Can a triangle have sides of 6 cm, 11 cm and 2 cm? (a) Yes (b) No
  20. 20.The two shorter sides of a right-angled triangle are 12 cm and 5 cm. How long is the longest side (in cm)?
  21. 21.In a right-angled triangle, one of the other two angles is 10°. What is the third angle (in degrees)?
  22. 22.An exterior angle of a triangle is 102°. One of its two interior opposite angles is 45°. What is the other one (in degrees)?
  23. 23.In a right-angled triangle, one of the other two angles is 31°. What is the third angle (in degrees)?
  24. 24.In a right-angled triangle, one of the other two angles is 22°. What is the third angle (in degrees)?
  25. 25.In an isosceles triangle, the two equal angles are 65° each. What is the third angle (in degrees)?
  26. 26.In an isosceles triangle, the angle between the two equal sides is 60°. What is each of the other two angles (in degrees)?
  27. 27.The two interior opposite angles of a triangle are 35° and 71°. What is the exterior angle (in degrees)?
  28. 28.In a right-angled triangle, one of the other two angles is 75°. What is the third angle (in degrees)?
  29. 29.The longest side of a right-angled triangle is 30 cm and one of the other sides is 18 cm. How long is the third side (in cm)?
  30. 30.In triangle ABC, angle A = 66° and angle B = 84°. What is angle C (in degrees)?
  31. 31.In a right-angled triangle, one of the other two angles is 24°. What is the third angle (in degrees)?
  32. 32.In a right-angled triangle, one of the other two angles is 68°. What is the third angle (in degrees)?
  33. 33.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  34. 34.The two interior opposite angles of a triangle are 24° and 52°. What is the exterior angle (in degrees)?
  35. 35.Can a triangle have sides of 9 cm, 20 cm and 9 cm? (a) Yes (b) No
  36. 36.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  37. 37.Can a triangle have sides of 9 cm, 12 cm and 5 cm? (a) No (b) Yes
  38. 38.In triangle ABC, angle A = 64° and angle B = 36°. What is angle C (in degrees)?
  39. 39.In an isosceles triangle, the angle between the two equal sides is 134°. What is each of the other two angles (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 60°. What is the third angle (in degrees)?

Answer key

  1. 107
  2. 138
  3. 94
  4. Yes
  5. 48
  6. 98
  7. 54
  8. 33
  9. 48
  10. 32
  11. 18
  12. 92
  13. 30
  14. No
  15. 93
  16. 61
  17. 7
  18. 102
  19. No
  20. 13
  21. 80
  22. 57
  23. 59
  24. 68
  25. 50
  26. 60
  27. 106
  28. 15
  29. 24
  30. 30
  31. 66
  32. 22
  33. 36
  34. 76
  35. No
  36. 25
  37. Yes
  38. 80
  39. 23
  40. 30

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