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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 310 · 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.

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  1. 1.The two shorter sides of a right-angled triangle are 10 cm and 24 cm. How long is the longest side (in cm)?
  2. 2.Can a triangle have sides of 12 cm, 20 cm and 6 cm? (a) No (b) Yes
  3. 3.In a right-angled triangle, one of the other two angles is 37°. What is the third angle (in degrees)?
  4. 4.The two interior opposite angles of a triangle are 65° and 36°. What is the exterior angle (in degrees)?
  5. 5.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  6. 6.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  7. 7.The two shorter sides of a right-angled triangle are 12 cm and 5 cm. How long is the longest side (in cm)?
  8. 8.In an isosceles triangle, the angle between the two equal sides is 78°. What is each of the other two angles (in degrees)?
  9. 9.An exterior angle of a triangle is 61°. One of its two interior opposite angles is 40°. What is the other one (in degrees)?
  10. 10.Can a triangle have sides of 5 cm, 4 cm and 2 cm? (a) No (b) Yes
  11. 11.Can a triangle have sides of 10 cm, 5 cm and 16 cm? (a) Yes (b) No
  12. 12.Can a triangle have sides of 9 cm, 7 cm and 4 cm? (a) No (b) Yes
  13. 13.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (in degrees)?
  14. 14.In an isosceles triangle, the two equal angles are 36° each. What is the third angle (in degrees)?
  15. 15.The longest side of a right-angled triangle is 5 cm and one of the other sides is 4 cm. How long is the third side (in cm)?
  16. 16.An exterior angle of a triangle is 110°. One of its two interior opposite angles is 37°. What is the other one (in degrees)?
  17. 17.The two interior opposite angles of a triangle are 44° and 20°. What is the exterior angle (in degrees)?
  18. 18.The two interior opposite angles of a triangle are 28° and 44°. What is the exterior angle (in degrees)?
  19. 19.An exterior angle of a triangle is 94°. One of its two interior opposite angles is 66°. What is the other one (in degrees)?
  20. 20.In triangle ABC, angle A = 56° and angle B = 30°. What is angle C (in degrees)?
  21. 21.An exterior angle of a triangle is 76°. One of its two interior opposite angles is 44°. What is the other one (in degrees)?
  22. 22.The angles of a triangle are in the ratio 1 : 2 : 2. What is the biggest angle (in degrees)?
  23. 23.Can a triangle have sides of 20 cm, 10 cm and 7 cm? (a) No (b) Yes
  24. 24.Can a triangle have sides of 7 cm, 6 cm and 2 cm? (a) Yes (b) No
  25. 25.In triangle ABC, angle A = 65° and angle B = 66°. What is angle C (in degrees)?
  26. 26.The two shorter sides of a right-angled triangle are 24 cm and 10 cm. How long is the longest side (in cm)?
  27. 27.The angles of a triangle are in the ratio 2 : 7 : 9. What is the biggest angle (in degrees)?
  28. 28.In a right-angled triangle, one of the other two angles is 48°. What is the third angle (in degrees)?
  29. 29.In an isosceles triangle, the angle between the two equal sides is 130°. What is each of the other two angles (in degrees)?
  30. 30.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  31. 31.In an isosceles triangle, the two equal angles are 32° each. What is the third angle (in degrees)?
  32. 32.In triangle ABC, angle A = 27° and angle B = 50°. What is angle C (in degrees)?
  33. 33.The two interior opposite angles of a triangle are 47° and 68°. What is the exterior angle (in degrees)?
  34. 34.In triangle ABC, angle A = 53° and angle B = 32°. What is angle C (in degrees)?
  35. 35.In a right-angled triangle, one of the other two angles is 53°. What is the third angle (in degrees)?
  36. 36.In triangle ABC, angle A = 49° and angle B = 53°. What is angle C (in degrees)?
  37. 37.Can a triangle have sides of 9 cm, 4 cm and 6 cm? (a) Yes (b) No
  38. 38.The two shorter sides of a right-angled triangle are 16 cm and 12 cm. How long is the longest side (in cm)?
  39. 39.In triangle ABC, angle A = 69° and angle B = 37°. What is angle C (in degrees)?
  40. 40.An exterior angle of a triangle is 41°. One of its two interior opposite angles is 21°. What is the other one (in degrees)?

Answer key

  1. 26
  2. No
  3. 53
  4. 101
  5. 25
  6. 17
  7. 13
  8. 51
  9. 21
  10. Yes
  11. No
  12. Yes
  13. 72
  14. 108
  15. 3
  16. 73
  17. 64
  18. 72
  19. 28
  20. 94
  21. 32
  22. 72
  23. No
  24. Yes
  25. 49
  26. 26
  27. 90
  28. 42
  29. 25
  30. 72
  31. 116
  32. 103
  33. 115
  34. 95
  35. 37
  36. 78
  37. Yes
  38. 20
  39. 74
  40. 20

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