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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 669 · 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 shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  2. 2.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  3. 3.In a right-angled triangle, one of the other two angles is 75°. What is the third angle (in degrees)?
  4. 4.Can a triangle have sides of 10 cm, 9 cm and 7 cm? (a) Yes (b) No
  5. 5.Can a triangle have sides of 7 cm, 3 cm and 12 cm? (a) No (b) Yes
  6. 6.In triangle ABC, angle A = 61° and angle B = 32°. What is angle C (in degrees)?
  7. 7.An exterior angle of a triangle is 91°. One of its two interior opposite angles is 68°. What is the other one (in degrees)?
  8. 8.The two interior opposite angles of a triangle are 38° and 47°. What is the exterior angle (in degrees)?
  9. 9.An exterior angle of a triangle is 47°. One of its two interior opposite angles is 25°. What is the other one (in degrees)?
  10. 10.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  11. 11.In an isosceles triangle, the angle between the two equal sides is 44°. What is each of the other two angles (in degrees)?
  12. 12.The two interior opposite angles of a triangle are 66° and 74°. What is the exterior angle (in degrees)?
  13. 13.In an isosceles triangle, the two equal angles are 49° each. What is the third angle (in degrees)?
  14. 14.In a right-angled triangle, one of the other two angles is 24°. What is the third angle (in degrees)?
  15. 15.The two interior opposite angles of a triangle are 21° and 70°. What is the exterior angle (in degrees)?
  16. 16.Can a triangle have sides of 22 cm, 12 cm and 9 cm? (a) Yes (b) No
  17. 17.In triangle ABC, angle A = 35° and angle B = 119°. What is angle C (in degrees)?
  18. 18.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)?
  19. 19.In a right-angled triangle, one of the other two angles is 27°. What is the third angle (in degrees)?
  20. 20.The two interior opposite angles of a triangle are 25° and 78°. What is the exterior angle (in degrees)?
  21. 21.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  22. 22.Can a triangle have sides of 4 cm, 10 cm and 12 cm? (a) No (b) Yes
  23. 23.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  24. 24.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)?
  25. 25.In triangle ABC, angle A = 48° and angle B = 91°. What is angle C (in degrees)?
  26. 26.In an isosceles triangle, the two equal angles are 25° each. What is the third angle (in degrees)?
  27. 27.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?
  28. 28.An exterior angle of a triangle is 113°. One of its two interior opposite angles is 36°. What is the other one (in degrees)?
  29. 29.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)?
  30. 30.An exterior angle of a triangle is 91°. One of its two interior opposite angles is 56°. What is the other one (in degrees)?
  31. 31.An exterior angle of a triangle is 121°. One of its two interior opposite angles is 71°. What is the other one (in degrees)?
  32. 32.Can a triangle have sides of 4 cm, 4 cm and 5 cm? (a) No (b) Yes
  33. 33.In an isosceles triangle, the two equal angles are 63° each. What is the third angle (in degrees)?
  34. 34.In a right-angled triangle, one of the other two angles is 35°. What is the third angle (in degrees)?
  35. 35.In a right-angled triangle, one of the other two angles is 12°. What is the third angle (in degrees)?
  36. 36.In a right-angled triangle, one of the other two angles is 44°. What is the third angle (in degrees)?
  37. 37.In an isosceles triangle, the two equal angles are 73° each. What is the third angle (in degrees)?
  38. 38.In an isosceles triangle, the angle between the two equal sides is 158°. What is each of the other two angles (in degrees)?
  39. 39.Can a triangle have sides of 21 cm, 11 cm and 8 cm? (a) No (b) Yes
  40. 40.The angles of a triangle are in the ratio 2 : 7 : 9. What is the biggest angle (in degrees)?

Answer key

  1. 25
  2. 45
  3. 15
  4. Yes
  5. No
  6. 87
  7. 23
  8. 85
  9. 22
  10. 80
  11. 68
  12. 140
  13. 82
  14. 66
  15. 91
  16. No
  17. 26
  18. 15
  19. 63
  20. 103
  21. 100
  22. Yes
  23. 20
  24. 7
  25. 41
  26. 130
  27. 48
  28. 77
  29. 8
  30. 35
  31. 50
  32. Yes
  33. 54
  34. 55
  35. 78
  36. 46
  37. 34
  38. 11
  39. No
  40. 90

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