← 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 688 · 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.An exterior angle of a triangle is 98°. One of its two interior opposite angles is 47°. What is the other one (in degrees)?
  2. 2.In triangle ABC, angle A = 26° and angle B = 58°. What is angle C (in degrees)?
  3. 3.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  4. 4.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  5. 5.In an isosceles triangle, the two equal angles are 53° each. What is the third angle (in degrees)?
  6. 6.In triangle ABC, angle A = 44° and angle B = 101°. What is angle C (in degrees)?
  7. 7.In triangle ABC, angle A = 46° and angle B = 83°. What is angle C (in degrees)?
  8. 8.In triangle ABC, angle A = 68° and angle B = 87°. What is angle C (in degrees)?
  9. 9.In a right-angled triangle, one of the other two angles is 59°. What is the third angle (in degrees)?
  10. 10.An exterior angle of a triangle is 107°. One of its two interior opposite angles is 39°. What is the other one (in degrees)?
  11. 11.In an isosceles triangle, the two equal angles are 69° each. What is the third angle (in degrees)?
  12. 12.Can a triangle have sides of 9 cm, 4 cm and 8 cm? (a) Yes (b) No
  13. 13.In an isosceles triangle, the angle between the two equal sides is 136°. What is each of the other two angles (in degrees)?
  14. 14.The angles of a triangle are in the ratio 3 : 3 : 4. What is the smallest angle (in degrees)?
  15. 15.In an isosceles triangle, the angle between the two equal sides is 156°. What is each of the other two angles (in degrees)?
  16. 16.In triangle ABC, angle A = 30° and angle B = 63°. What is angle C (in degrees)?
  17. 17.In triangle ABC, angle A = 52° and angle B = 24°. What is angle C (in degrees)?
  18. 18.In an isosceles triangle, the angle between the two equal sides is 56°. What is each of the other two angles (in degrees)?
  19. 19.An exterior angle of a triangle is 128°. One of its two interior opposite angles is 71°. What is the other one (in degrees)?
  20. 20.Can a triangle have sides of 8 cm, 2 cm and 8 cm? (a) No (b) Yes
  21. 21.In triangle ABC, angle A = 80° and angle B = 32°. What is angle C (in degrees)?
  22. 22.Can a triangle have sides of 7 cm, 6 cm and 3 cm? (a) Yes (b) No
  23. 23.The two interior opposite angles of a triangle are 57° and 79°. What is the exterior angle (in degrees)?
  24. 24.In triangle ABC, angle A = 66° and angle B = 67°. What is angle C (in degrees)?
  25. 25.In a right-angled triangle, one of the other two angles is 79°. What is the third angle (in degrees)?
  26. 26.In triangle ABC, angle A = 22° and angle B = 80°. What is angle C (in degrees)?
  27. 27.In triangle ABC, angle A = 37° and angle B = 77°. What is angle C (in degrees)?
  28. 28.Can a triangle have sides of 9 cm, 11 cm and 2 cm? (a) No (b) Yes
  29. 29.The two interior opposite angles of a triangle are 49° and 75°. 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 47°. What is the other one (in degrees)?
  31. 31.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  32. 32.An exterior angle of a triangle is 135°. One of its two interior opposite angles is 58°. What is the other one (in degrees)?
  33. 33.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  34. 34.The two shorter sides of a right-angled triangle are 8 cm and 6 cm. How long is the longest side (in cm)?
  35. 35.The two interior opposite angles of a triangle are 31° and 41°. What is the exterior angle (in degrees)?
  36. 36.In a right-angled triangle, one of the other two angles is 37°. What is the third angle (in degrees)?
  37. 37.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)?
  38. 38.The two interior opposite angles of a triangle are 78° and 64°. What is the exterior angle (in degrees)?
  39. 39.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  40. 40.In an isosceles triangle, the angle between the two equal sides is 24°. What is each of the other two angles (in degrees)?

Answer key

  1. 51
  2. 96
  3. 17
  4. 36
  5. 74
  6. 35
  7. 51
  8. 25
  9. 31
  10. 68
  11. 42
  12. Yes
  13. 22
  14. 54
  15. 12
  16. 87
  17. 104
  18. 62
  19. 57
  20. Yes
  21. 68
  22. Yes
  23. 136
  24. 47
  25. 11
  26. 78
  27. 66
  28. No
  29. 124
  30. 35
  31. 120
  32. 77
  33. 90
  34. 10
  35. 72
  36. 53
  37. 8
  38. 142
  39. 90
  40. 78

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