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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 230 · 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 50° and 27°. What is the exterior angle (in degrees)?
  2. 2.In a right-angled triangle, one of the other two angles is 13°. What is the third angle (in degrees)?
  3. 3.The two interior opposite angles of a triangle are 69° and 50°. What is the exterior angle (in degrees)?
  4. 4.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  5. 5.In triangle ABC, angle A = 52° and angle B = 67°. What is angle C (in degrees)?
  6. 6.In a right-angled triangle, one of the other two angles is 69°. What is the third angle (in degrees)?
  7. 7.In a right-angled triangle, one of the other two angles is 31°. What is the third angle (in degrees)?
  8. 8.Can a triangle have sides of 10 cm, 3 cm and 17 cm? (a) Yes (b) No
  9. 9.The two interior opposite angles of a triangle are 38° and 49°. What is the exterior angle (in degrees)?
  10. 10.In triangle ABC, angle A = 75° and angle B = 23°. What is angle C (in degrees)?
  11. 11.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)?
  12. 12.Can a triangle have sides of 8 cm, 12 cm and 4 cm? (a) No (b) Yes
  13. 13.The two interior opposite angles of a triangle are 67° and 23°. What is the exterior angle (in degrees)?
  14. 14.Can a triangle have sides of 6 cm, 10 cm and 6 cm? (a) Yes (b) No
  15. 15.Can a triangle have sides of 11 cm, 5 cm and 4 cm? (a) No (b) Yes
  16. 16.The angles of a triangle are in the ratio 1 : 2 : 2. What is the smallest angle (in degrees)?
  17. 17.In an isosceles triangle, the angle between the two equal sides is 64°. What is each of the other two angles (in degrees)?
  18. 18.The angles of a triangle are in the ratio 3 : 5 : 7. What is the biggest angle (in degrees)?
  19. 19.In triangle ABC, angle A = 26° and angle B = 93°. What is angle C (in degrees)?
  20. 20.Can a triangle have sides of 12 cm, 18 cm and 3 cm? (a) Yes (b) No
  21. 21.An exterior angle of a triangle is 93°. One of its two interior opposite angles is 23°. What is the other one (in degrees)?
  22. 22.Can a triangle have sides of 3 cm, 9 cm and 13 cm? (a) Yes (b) No
  23. 23.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  24. 24.An exterior angle of a triangle is 120°. One of its two interior opposite angles is 68°. What is the other one (in degrees)?
  25. 25.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  26. 26.In a right-angled triangle, one of the other two angles is 74°. What is the third angle (in degrees)?
  27. 27.The two interior opposite angles of a triangle are 71° and 49°. What is the exterior angle (in degrees)?
  28. 28.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  29. 29.The longest side of a right-angled triangle is 15 cm and one of the other sides is 9 cm. How long is the third side (in cm)?
  30. 30.In a right-angled triangle, one of the other two angles is 57°. What is the third angle (in degrees)?
  31. 31.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?
  32. 32.The two shorter sides of a right-angled triangle are 3 cm and 4 cm. How long is the longest side (in cm)?
  33. 33.The two interior opposite angles of a triangle are 32° and 33°. What is the exterior angle (in degrees)?
  34. 34.In triangle ABC, angle A = 63° and angle B = 51°. What is angle C (in degrees)?
  35. 35.The two shorter sides of a right-angled triangle are 5 cm and 12 cm. How long is the longest side (in cm)?
  36. 36.In triangle ABC, angle A = 31° and angle B = 118°. What is angle C (in degrees)?
  37. 37.The longest side of a right-angled triangle is 25 cm and one of the other sides is 20 cm. How long is the third side (in cm)?
  38. 38.In triangle ABC, angle A = 25° and angle B = 131°. What is angle C (in degrees)?
  39. 39.In an isosceles triangle, the angle between the two equal sides is 112°. What is each of the other two angles (in degrees)?
  40. 40.In triangle ABC, angle A = 33° and angle B = 104°. What is angle C (in degrees)?

Answer key

  1. 77
  2. 77
  3. 119
  4. 120
  5. 61
  6. 21
  7. 59
  8. No
  9. 87
  10. 82
  11. 7
  12. No
  13. 90
  14. Yes
  15. No
  16. 36
  17. 58
  18. 84
  19. 61
  20. No
  21. 70
  22. No
  23. 25
  24. 52
  25. 20
  26. 16
  27. 120
  28. 72
  29. 12
  30. 33
  31. 48
  32. 5
  33. 65
  34. 66
  35. 13
  36. 31
  37. 15
  38. 24
  39. 34
  40. 43

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