← 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 276 · 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 27° each. What is the third angle (in degrees)?
  2. 2.The two interior opposite angles of a triangle are 63° and 53°. What is the exterior angle (in degrees)?
  3. 3.In a right-angled triangle, one of the other two angles is 79°. What is the third angle (in degrees)?
  4. 4.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  5. 5.In triangle ABC, angle A = 37° and angle B = 46°. What is angle C (in degrees)?
  6. 6.In a right-angled triangle, one of the other two angles is 27°. What is the third angle (in degrees)?
  7. 7.In triangle ABC, angle A = 83° and angle B = 65°. What is angle C (in degrees)?
  8. 8.In triangle ABC, angle A = 40° and angle B = 60°. What is angle C (in degrees)?
  9. 9.In triangle ABC, angle A = 82° and angle B = 49°. What is angle C (in degrees)?
  10. 10.In a right-angled triangle, one of the other two angles is 28°. What is the third angle (in degrees)?
  11. 11.In a right-angled triangle, one of the other two angles is 58°. What is the third angle (in degrees)?
  12. 12.In an isosceles triangle, the angle between the two equal sides is 78°. What is each of the other two angles (in degrees)?
  13. 13.In a right-angled triangle, one of the other two angles is 50°. What is the third angle (in degrees)?
  14. 14.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  15. 15.The two interior opposite angles of a triangle are 74° and 52°. What is the exterior angle (in degrees)?
  16. 16.In triangle ABC, angle A = 55° and angle B = 94°. What is angle C (in degrees)?
  17. 17.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  18. 18.The longest side of a right-angled triangle is 39 cm and one of the other sides is 36 cm. How long is the third side (in cm)?
  19. 19.Can a triangle have sides of 24 cm, 11 cm and 9 cm? (a) No (b) Yes
  20. 20.In an isosceles triangle, the angle between the two equal sides is 50°. What is each of the other two angles (in degrees)?
  21. 21.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  22. 22.An exterior angle of a triangle is 82°. One of its two interior opposite angles is 41°. What is the other one (in degrees)?
  23. 23.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)?
  24. 24.In triangle ABC, angle A = 40° and angle B = 54°. What is angle C (in degrees)?
  25. 25.In an isosceles triangle, the two equal angles are 84° each. What is the third angle (in degrees)?
  26. 26.The angles of a triangle are in the ratio 1 : 2 : 2. What is the biggest angle (in degrees)?
  27. 27.In triangle ABC, angle A = 79° and angle B = 50°. What is angle C (in degrees)?
  28. 28.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)?
  29. 29.The two interior opposite angles of a triangle are 42° and 23°. What is the exterior angle (in degrees)?
  30. 30.An exterior angle of a triangle is 82°. One of its two interior opposite angles is 59°. What is the other one (in degrees)?
  31. 31.The two interior opposite angles of a triangle are 30° and 30°. What is the exterior angle (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.In a right-angled triangle, one of the other two angles is 19°. What is the third angle (in degrees)?
  34. 34.An exterior angle of a triangle is 138°. One of its two interior opposite angles is 63°. What is the other one (in degrees)?
  35. 35.Can a triangle have sides of 3 cm, 4 cm and 3 cm? (a) No (b) Yes
  36. 36.Can a triangle have sides of 13 cm, 3 cm and 5 cm? (a) Yes (b) No
  37. 37.In a right-angled triangle, one of the other two angles is 12°. What is the third angle (in degrees)?
  38. 38.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)?
  39. 39.The angles of a triangle are in the ratio 5 : 6 : 7. What is the biggest angle (in degrees)?
  40. 40.In triangle ABC, angle A = 40° and angle B = 100°. What is angle C (in degrees)?

Answer key

  1. 126
  2. 116
  3. 11
  4. 90
  5. 97
  6. 63
  7. 32
  8. 80
  9. 49
  10. 62
  11. 32
  12. 51
  13. 40
  14. 17
  15. 126
  16. 31
  17. 100
  18. 15
  19. No
  20. 65
  21. 72
  22. 41
  23. 7
  24. 86
  25. 12
  26. 72
  27. 51
  28. 8
  29. 65
  30. 23
  31. 60
  32. 25
  33. 71
  34. 75
  35. Yes
  36. No
  37. 78
  38. 8
  39. 70
  40. 40

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