← 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 259 · 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 3 : 3 : 4. What is the biggest angle (in degrees)?
  2. 2.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)?
  3. 3.The longest side of a right-angled triangle is 10 cm and one of the other sides is 8 cm. How long is the third side (in cm)?
  4. 4.The two interior opposite angles of a triangle are 79° and 44°. What is the exterior angle (in degrees)?
  5. 5.An exterior angle of a triangle is 117°. One of its two interior opposite angles is 39°. What is the other one (in degrees)?
  6. 6.In triangle ABC, angle A = 89° and angle B = 57°. What is angle C (in degrees)?
  7. 7.Can a triangle have sides of 6 cm, 6 cm and 7 cm? (a) Yes (b) No
  8. 8.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  9. 9.The angles of a triangle are in the ratio 3 : 5 : 7. What is the biggest angle (in degrees)?
  10. 10.In triangle ABC, angle A = 81° and angle B = 50°. What is angle C (in degrees)?
  11. 11.In triangle ABC, angle A = 48° and angle B = 61°. What is angle C (in degrees)?
  12. 12.In triangle ABC, angle A = 93° and angle B = 22°. What is angle C (in degrees)?
  13. 13.In triangle ABC, angle A = 42° and angle B = 59°. What is angle C (in degrees)?
  14. 14.An exterior angle of a triangle is 93°. One of its two interior opposite angles is 28°. What is the other one (in degrees)?
  15. 15.An exterior angle of a triangle is 64°. One of its two interior opposite angles is 37°. What is the other one (in degrees)?
  16. 16.In an isosceles triangle, the angle between the two equal sides is 58°. What is each of the other two angles (in degrees)?
  17. 17.The two interior opposite angles of a triangle are 80° and 73°. What is the exterior angle (in degrees)?
  18. 18.In a right-angled triangle, one of the other two angles is 75°. What is the third angle (in degrees)?
  19. 19.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  20. 20.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  21. 21.In triangle ABC, angle A = 39° and angle B = 117°. What is angle C (in degrees)?
  22. 22.The two interior opposite angles of a triangle are 72° and 53°. What is the exterior angle (in degrees)?
  23. 23.In an isosceles triangle, the angle between the two equal sides is 46°. What is each of the other two angles (in degrees)?
  24. 24.In triangle ABC, angle A = 97° and angle B = 59°. What is angle C (in degrees)?
  25. 25.The two interior opposite angles of a triangle are 77° and 78°. What is the exterior angle (in degrees)?
  26. 26.In an isosceles triangle, the angle between the two equal sides is 84°. What is each of the other two angles (in degrees)?
  27. 27.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)?
  28. 28.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  29. 29.In an isosceles triangle, the two equal angles are 63° each. What is the third angle (in degrees)?
  30. 30.In an isosceles triangle, the angle between the two equal sides is 60°. What is each of the other two angles (in degrees)?
  31. 31.The two shorter sides of a right-angled triangle are 24 cm and 18 cm. How long is the longest side (in cm)?
  32. 32.In triangle ABC, angle A = 39° and angle B = 54°. What is angle C (in degrees)?
  33. 33.Can a triangle have sides of 8 cm, 12 cm and 10 cm? (a) Yes (b) No
  34. 34.Can a triangle have sides of 13 cm, 9 cm and 7 cm? (a) No (b) Yes
  35. 35.In an isosceles triangle, the two equal angles are 22° each. What is the third angle (in degrees)?
  36. 36.In triangle ABC, angle A = 43° and angle B = 41°. What is angle C (in degrees)?
  37. 37.Can a triangle have sides of 12 cm, 3 cm and 17 cm? (a) No (b) Yes
  38. 38.In a right-angled triangle, one of the other two angles is 58°. What is the third angle (in degrees)?
  39. 39.The two interior opposite angles of a triangle are 72° and 27°. What is the exterior angle (in degrees)?
  40. 40.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?

Answer key

  1. 72
  2. 8
  3. 6
  4. 123
  5. 78
  6. 34
  7. Yes
  8. 40
  9. 84
  10. 49
  11. 71
  12. 65
  13. 79
  14. 65
  15. 27
  16. 61
  17. 153
  18. 15
  19. 90
  20. 25
  21. 24
  22. 125
  23. 67
  24. 24
  25. 155
  26. 48
  27. 24
  28. 18
  29. 54
  30. 60
  31. 30
  32. 87
  33. Yes
  34. Yes
  35. 136
  36. 96
  37. No
  38. 32
  39. 99
  40. 48

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