← 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 382 · 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 angles of a triangle are in the ratio 1 : 2 : 3. What is the biggest angle (in degrees)?
  2. 2.The two interior opposite angles of a triangle are 61° and 34°. What is the exterior angle (in degrees)?
  3. 3.In an isosceles triangle, the angle between the two equal sides is 44°. What is each of the other two angles (in degrees)?
  4. 4.Can a triangle have sides of 6 cm, 3 cm and 3 cm? (a) Yes (b) No
  5. 5.In a right-angled triangle, one of the other two angles is 17°. What is the third angle (in degrees)?
  6. 6.In a right-angled triangle, one of the other two angles is 78°. What is the third angle (in degrees)?
  7. 7.In an isosceles triangle, the angle between the two equal sides is 148°. What is each of the other two angles (in degrees)?
  8. 8.An exterior angle of a triangle is 69°. One of its two interior opposite angles is 34°. What is the other one (in degrees)?
  9. 9.The longest side of a right-angled triangle is 25 cm and one of the other sides is 7 cm. How long is the third side (in cm)?
  10. 10.The two interior opposite angles of a triangle are 39° and 36°. What is the exterior angle (in degrees)?
  11. 11.In an isosceles triangle, the angle between the two equal sides is 88°. What is each of the other two angles (in degrees)?
  12. 12.An exterior angle of a triangle is 105°. One of its two interior opposite angles is 71°. What is the other one (in degrees)?
  13. 13.In an isosceles triangle, the angle between the two equal sides is 32°. What is each of the other two angles (in degrees)?
  14. 14.In triangle ABC, angle A = 39° and angle B = 38°. What is angle C (in degrees)?
  15. 15.In a right-angled triangle, one of the other two angles is 47°. What is the third angle (in degrees)?
  16. 16.In a right-angled triangle, one of the other two angles is 66°. What is the third angle (in degrees)?
  17. 17.The angles of a triangle are in the ratio 2 : 2 : 5. What is the smallest angle (in degrees)?
  18. 18.In an isosceles triangle, the two equal angles are 49° each. What is the third angle (in degrees)?
  19. 19.In triangle ABC, angle A = 79° and angle B = 69°. What is angle C (in degrees)?
  20. 20.In an isosceles triangle, the two equal angles are 29° each. What is the third angle (in degrees)?
  21. 21.In a right-angled triangle, one of the other two angles is 63°. What is the third angle (in degrees)?
  22. 22.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  23. 23.In an isosceles triangle, the two equal angles are 64° each. What is the third angle (in degrees)?
  24. 24.The angles of a triangle are in the ratio 1 : 2 : 3. What is the smallest angle (in degrees)?
  25. 25.In a right-angled triangle, one of the other two angles is 40°. What is the third angle (in degrees)?
  26. 26.Can a triangle have sides of 9 cm, 9 cm and 21 cm? (a) Yes (b) No
  27. 27.Can a triangle have sides of 6 cm, 5 cm and 2 cm? (a) No (b) Yes
  28. 28.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  29. 29.In triangle ABC, angle A = 84° and angle B = 52°. What is angle C (in degrees)?
  30. 30.An exterior angle of a triangle is 94°. One of its two interior opposite angles is 43°. What is the other one (in degrees)?
  31. 31.In an isosceles triangle, the angle between the two equal sides is 40°. What is each of the other two angles (in degrees)?
  32. 32.In an isosceles triangle, the two equal angles are 80° each. What is the third angle (in degrees)?
  33. 33.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  34. 34.The angles of a triangle are in the ratio 1 : 2 : 6. What is the smallest angle (in degrees)?
  35. 35.Can a triangle have sides of 7 cm, 2 cm and 5 cm? (a) Yes (b) No
  36. 36.The longest side of a right-angled triangle is 13 cm and one of the other sides is 5 cm. How long is the third side (in cm)?
  37. 37.In triangle ABC, angle A = 25° and angle B = 33°. What is angle C (in degrees)?
  38. 38.In triangle ABC, angle A = 39° and angle B = 105°. What is angle C (in degrees)?
  39. 39.An exterior angle of a triangle is 70°. One of its two interior opposite angles is 49°. What is the other one (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 22°. What is the third angle (in degrees)?

Answer key

  1. 90
  2. 95
  3. 68
  4. No
  5. 73
  6. 12
  7. 16
  8. 35
  9. 24
  10. 75
  11. 46
  12. 34
  13. 74
  14. 103
  15. 43
  16. 24
  17. 40
  18. 82
  19. 32
  20. 122
  21. 27
  22. 90
  23. 52
  24. 30
  25. 50
  26. No
  27. Yes
  28. 17
  29. 44
  30. 51
  31. 70
  32. 20
  33. 75
  34. 20
  35. No
  36. 12
  37. 122
  38. 36
  39. 21
  40. 68

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