← 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 877 · 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 : 4 : 5. What is the biggest angle (in degrees)?
  2. 2.In triangle ABC, angle A = 83° and angle B = 65°. What is angle C (in degrees)?
  3. 3.In an isosceles triangle, the angle between the two equal sides is 106°. What is each of the other two angles (in degrees)?
  4. 4.In an isosceles triangle, the angle between the two equal sides is 40°. What is each of the other two angles (in degrees)?
  5. 5.In an isosceles triangle, the angle between the two equal sides is 78°. What is each of the other two angles (in degrees)?
  6. 6.The two interior opposite angles of a triangle are 29° and 79°. What is the exterior angle (in degrees)?
  7. 7.In a right-angled triangle, one of the other two angles is 23°. What is the third angle (in degrees)?
  8. 8.Can a triangle have sides of 5 cm, 11 cm and 12 cm? (a) Yes (b) No
  9. 9.The two interior opposite angles of a triangle are 20° and 73°. What is the exterior angle (in degrees)?
  10. 10.In triangle ABC, angle A = 90° and angle B = 39°. What is angle C (in degrees)?
  11. 11.An exterior angle of a triangle is 127°. One of its two interior opposite angles is 56°. What is the other one (in degrees)?
  12. 12.The two interior opposite angles of a triangle are 64° and 79°. What is the exterior angle (in degrees)?
  13. 13.In triangle ABC, angle A = 41° and angle B = 44°. What is angle C (in degrees)?
  14. 14.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  15. 15.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)?
  16. 16.The angles of a triangle are in the ratio 1 : 2 : 6. What is the smallest angle (in degrees)?
  17. 17.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  18. 18.The angles of a triangle are in the ratio 5 : 6 : 7. What is the biggest angle (in degrees)?
  19. 19.In an isosceles triangle, the angle between the two equal sides is 20°. What is each of the other two angles (in degrees)?
  20. 20.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  21. 21.An exterior angle of a triangle is 115°. One of its two interior opposite angles is 51°. What is the other one (in degrees)?
  22. 22.In a right-angled triangle, one of the other two angles is 70°. What is the third angle (in degrees)?
  23. 23.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?
  24. 24.In triangle ABC, angle A = 34° and angle B = 105°. What is angle C (in degrees)?
  25. 25.In an isosceles triangle, the angle between the two equal sides is 96°. What is each of the other two angles (in degrees)?
  26. 26.The two shorter sides of a right-angled triangle are 15 cm and 20 cm. How long is the longest side (in cm)?
  27. 27.In an isosceles triangle, the angle between the two equal sides is 76°. What is each of the other two angles (in degrees)?
  28. 28.The longest side of a right-angled triangle is 5 cm and one of the other sides is 3 cm. How long is the third side (in cm)?
  29. 29.The longest side of a right-angled triangle is 17 cm and one of the other sides is 8 cm. How long is the third side (in cm)?
  30. 30.In an isosceles triangle, the angle between the two equal sides is 82°. What is each of the other two angles (in degrees)?
  31. 31.In triangle ABC, angle A = 46° and angle B = 110°. What is angle C (in degrees)?
  32. 32.In triangle ABC, angle A = 64° and angle B = 94°. What is angle C (in degrees)?
  33. 33.In triangle ABC, angle A = 72° and angle B = 42°. What is angle C (in degrees)?
  34. 34.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  35. 35.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)?
  36. 36.In an isosceles triangle, the angle between the two equal sides is 58°. What is each of the other two angles (in degrees)?
  37. 37.In an isosceles triangle, the two equal angles are 38° each. What is the third angle (in degrees)?
  38. 38.In a right-angled triangle, one of the other two angles is 22°. What is the third angle (in degrees)?
  39. 39.The two interior opposite angles of a triangle are 31° and 37°. What is the exterior angle (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 52°. What is the third angle (in degrees)?

Answer key

  1. 90
  2. 32
  3. 37
  4. 70
  5. 51
  6. 108
  7. 67
  8. Yes
  9. 93
  10. 51
  11. 71
  12. 143
  13. 95
  14. 17
  15. 24
  16. 20
  17. 36
  18. 70
  19. 80
  20. 90
  21. 64
  22. 20
  23. 50
  24. 41
  25. 42
  26. 25
  27. 52
  28. 4
  29. 15
  30. 49
  31. 24
  32. 22
  33. 66
  34. 40
  35. 8
  36. 61
  37. 104
  38. 68
  39. 68
  40. 38

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