← 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 679 · 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 46° and 36°. What is the exterior angle (in degrees)?
  2. 2.An exterior angle of a triangle is 86°. One of its two interior opposite angles is 53°. What is the other one (in degrees)?
  3. 3.In an isosceles triangle, the angle between the two equal sides is 124°. What is each of the other two angles (in degrees)?
  4. 4.In a right-angled triangle, one of the other two angles is 28°. What is the third angle (in degrees)?
  5. 5.The two interior opposite angles of a triangle are 80° and 62°. What is the exterior angle (in degrees)?
  6. 6.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  7. 7.Can a triangle have sides of 12 cm, 2 cm and 12 cm? (a) No (b) Yes
  8. 8.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)?
  9. 9.An exterior angle of a triangle is 102°. One of its two interior opposite angles is 23°. What is the other one (in degrees)?
  10. 10.Can a triangle have sides of 5 cm, 6 cm and 7 cm? (a) Yes (b) No
  11. 11.An exterior angle of a triangle is 88°. One of its two interior opposite angles is 42°. What is the other one (in degrees)?
  12. 12.An exterior angle of a triangle is 67°. One of its two interior opposite angles is 26°. What is the other one (in degrees)?
  13. 13.In triangle ABC, angle A = 20° and angle B = 121°. What is angle C (in degrees)?
  14. 14.In triangle ABC, angle A = 38° and angle B = 26°. What is angle C (in degrees)?
  15. 15.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)?
  16. 16.In triangle ABC, angle A = 27° and angle B = 72°. What is angle C (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 angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (in degrees)?
  19. 19.Can a triangle have sides of 10 cm, 26 cm and 12 cm? (a) Yes (b) No
  20. 20.Can a triangle have sides of 7 cm, 12 cm and 11 cm? (a) Yes (b) No
  21. 21.The two interior opposite angles of a triangle are 29° and 67°. What is the exterior angle (in degrees)?
  22. 22.In an isosceles triangle, the angle between the two equal sides is 128°. What is each of the other two angles (in degrees)?
  23. 23.An exterior angle of a triangle is 141°. One of its two interior opposite angles is 69°. What is the other one (in degrees)?
  24. 24.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  25. 25.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  26. 26.In a right-angled triangle, one of the other two angles is 25°. What is the third angle (in degrees)?
  27. 27.Can a triangle have sides of 14 cm, 3 cm and 6 cm? (a) Yes (b) No
  28. 28.In triangle ABC, angle A = 27° and angle B = 86°. What is angle C (in degrees)?
  29. 29.In triangle ABC, angle A = 69° and angle B = 63°. What is angle C (in degrees)?
  30. 30.The two interior opposite angles of a triangle are 46° and 77°. What is the exterior angle (in degrees)?
  31. 31.In an isosceles triangle, the two equal angles are 28° each. What is the third angle (in degrees)?
  32. 32.In a right-angled triangle, one of the other two angles is 74°. What is the third angle (in degrees)?
  33. 33.An exterior angle of a triangle is 59°. One of its two interior opposite angles is 32°. What is the other one (in degrees)?
  34. 34.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  35. 35.Can a triangle have sides of 11 cm, 10 cm and 8 cm? (a) Yes (b) No
  36. 36.An exterior angle of a triangle is 105°. One of its two interior opposite angles is 70°. What is the other one (in degrees)?
  37. 37.In triangle ABC, angle A = 39° and angle B = 44°. What is angle C (in degrees)?
  38. 38.An exterior angle of a triangle is 54°. One of its two interior opposite angles is 25°. What is the other one (in degrees)?
  39. 39.In triangle ABC, angle A = 53° and angle B = 62°. What is angle C (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 18°. What is the third angle (in degrees)?

Answer key

  1. 82
  2. 33
  3. 28
  4. 62
  5. 142
  6. 90
  7. Yes
  8. 24
  9. 79
  10. Yes
  11. 46
  12. 41
  13. 39
  14. 116
  15. 8
  16. 81
  17. 7
  18. 72
  19. No
  20. Yes
  21. 96
  22. 26
  23. 72
  24. 18
  25. 25
  26. 65
  27. No
  28. 67
  29. 48
  30. 123
  31. 124
  32. 16
  33. 27
  34. 36
  35. Yes
  36. 35
  37. 97
  38. 29
  39. 65
  40. 72

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