← 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 935 · 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.Can a triangle have sides of 7 cm, 11 cm and 7 cm? (a) Yes (b) No
  2. 2.In a right-angled triangle, one of the other two angles is 38°. What is the third angle (in degrees)?
  3. 3.In triangle ABC, angle A = 22° and angle B = 55°. What is angle C (in degrees)?
  4. 4.In triangle ABC, angle A = 43° and angle B = 40°. What is angle C (in degrees)?
  5. 5.In a right-angled triangle, one of the other two angles is 22°. What is the third angle (in degrees)?
  6. 6.In an isosceles triangle, the angle between the two equal sides is 92°. What is each of the other two angles (in degrees)?
  7. 7.The angles of a triangle are in the ratio 1 : 2 : 3. What is the biggest angle (in degrees)?
  8. 8.The longest side of a right-angled triangle is 39 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  9. 9.Can a triangle have sides of 13 cm, 4 cm and 8 cm? (a) Yes (b) No
  10. 10.The two interior opposite angles of a triangle are 62° and 48°. What is the exterior angle (in degrees)?
  11. 11.An exterior angle of a triangle is 72°. One of its two interior opposite angles is 20°. What is the other one (in degrees)?
  12. 12.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  13. 13.An exterior angle of a triangle is 133°. One of its two interior opposite angles is 61°. What is the other one (in degrees)?
  14. 14.The two interior opposite angles of a triangle are 71° and 62°. What is the exterior angle (in degrees)?
  15. 15.The longest side of a right-angled triangle is 13 cm and one of the other sides is 12 cm. How long is the third side (in cm)?
  16. 16.The longest side of a right-angled triangle is 15 cm and one of the other sides is 12 cm. How long is the third side (in cm)?
  17. 17.In an isosceles triangle, the angle between the two equal sides is 104°. What is each of the other two angles (in degrees)?
  18. 18.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  19. 19.In an isosceles triangle, the angle between the two equal sides is 106°. What is each of the other two angles (in degrees)?
  20. 20.In a right-angled triangle, one of the other two angles is 25°. What is the third angle (in degrees)?
  21. 21.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  22. 22.In an isosceles triangle, the angle between the two equal sides is 126°. What is each of the other two angles (in degrees)?
  23. 23.In a right-angled triangle, one of the other two angles is 70°. What is the third angle (in degrees)?
  24. 24.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  25. 25.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)?
  26. 26.An exterior angle of a triangle is 81°. One of its two interior opposite angles is 21°. What is the other one (in degrees)?
  27. 27.Can a triangle have sides of 11 cm, 10 cm and 6 cm? (a) No (b) Yes
  28. 28.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (in degrees)?
  29. 29.In triangle ABC, angle A = 57° and angle B = 39°. What is angle C (in degrees)?
  30. 30.In a right-angled triangle, one of the other two angles is 63°. What is the third angle (in degrees)?
  31. 31.Can a triangle have sides of 7 cm, 16 cm and 7 cm? (a) Yes (b) No
  32. 32.In triangle ABC, angle A = 31° and angle B = 108°. What is angle C (in degrees)?
  33. 33.An exterior angle of a triangle is 90°. One of its two interior opposite angles is 29°. What is the other one (in degrees)?
  34. 34.An exterior angle of a triangle is 132°. One of its two interior opposite angles is 64°. What is the other one (in degrees)?
  35. 35.In triangle ABC, angle A = 99° and angle B = 46°. What is angle C (in degrees)?
  36. 36.In a right-angled triangle, one of the other two angles is 12°. What is the third angle (in degrees)?
  37. 37.Can a triangle have sides of 10 cm, 7 cm and 6 cm? (a) Yes (b) No
  38. 38.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  39. 39.In triangle ABC, angle A = 33° and angle B = 27°. What is angle C (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 56°. What is the third angle (in degrees)?

Answer key

  1. Yes
  2. 52
  3. 103
  4. 97
  5. 68
  6. 44
  7. 90
  8. 36
  9. No
  10. 110
  11. 52
  12. 17
  13. 72
  14. 133
  15. 5
  16. 9
  17. 38
  18. 25
  19. 37
  20. 65
  21. 75
  22. 27
  23. 20
  24. 120
  25. 4
  26. 60
  27. Yes
  28. 72
  29. 84
  30. 27
  31. No
  32. 41
  33. 61
  34. 68
  35. 35
  36. 78
  37. Yes
  38. 40
  39. 120
  40. 34

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