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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 424 · 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.Can a triangle have sides of 9 cm, 9 cm and 16 cm? (a) Yes (b) No
  2. 2.In an isosceles triangle, the two equal angles are 85° each. What is the third angle (in degrees)?
  3. 3.Can a triangle have sides of 9 cm, 15 cm and 9 cm? (a) Yes (b) No
  4. 4.The angles of a triangle are in the ratio 1 : 1 : 2. What is the smallest angle (in degrees)?
  5. 5.In triangle ABC, angle A = 44° and angle B = 109°. What is angle C (in degrees)?
  6. 6.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  7. 7.In a right-angled triangle, one of the other two angles is 56°. What is the third angle (in degrees)?
  8. 8.In a right-angled triangle, one of the other two angles is 37°. What is the third angle (in degrees)?
  9. 9.The two interior opposite angles of a triangle are 49° and 38°. What is the exterior angle (in degrees)?
  10. 10.The angles of a triangle are in the ratio 2 : 2 : 5. What is the smallest angle (in degrees)?
  11. 11.In triangle ABC, angle A = 84° and angle B = 41°. What is angle C (in degrees)?
  12. 12.Can a triangle have sides of 7 cm, 8 cm and 13 cm? (a) Yes (b) No
  13. 13.In a right-angled triangle, one of the other two angles is 32°. What is the third angle (in degrees)?
  14. 14.The two interior opposite angles of a triangle are 37° and 56°. What is the exterior angle (in degrees)?
  15. 15.In an isosceles triangle, the two equal angles are 78° each. What is the third angle (in degrees)?
  16. 16.The two interior opposite angles of a triangle are 71° and 57°. What is the exterior angle (in degrees)?
  17. 17.In triangle ABC, angle A = 75° and angle B = 62°. What is angle C (in degrees)?
  18. 18.Can a triangle have sides of 4 cm, 10 cm and 9 cm? (a) No (b) Yes
  19. 19.In an isosceles triangle, the two equal angles are 69° each. What is the third angle (in degrees)?
  20. 20.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  21. 21.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  22. 22.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)?
  23. 23.The two shorter sides of a right-angled triangle are 20 cm and 15 cm. How long is the longest side (in cm)?
  24. 24.The two shorter sides of a right-angled triangle are 6 cm and 8 cm. How long is the longest side (in cm)?
  25. 25.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  26. 26.In an isosceles triangle, the two equal angles are 56° each. What is the third angle (in degrees)?
  27. 27.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  28. 28.Can a triangle have sides of 5 cm, 6 cm and 9 cm? (a) No (b) Yes
  29. 29.The angles of a triangle are in the ratio 2 : 3 : 5. What is the smallest angle (in degrees)?
  30. 30.In a right-angled triangle, one of the other two angles is 52°. What is the third angle (in degrees)?
  31. 31.In triangle ABC, angle A = 35° and angle B = 45°. What is angle C (in degrees)?
  32. 32.The two interior opposite angles of a triangle are 65° and 53°. What is the exterior angle (in degrees)?
  33. 33.The two interior opposite angles of a triangle are 38° and 40°. What is the exterior angle (in degrees)?
  34. 34.In a right-angled triangle, one of the other two angles is 29°. What is the third angle (in degrees)?
  35. 35.In an isosceles triangle, the angle between the two equal sides is 36°. What is each of the other two angles (in degrees)?
  36. 36.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)?
  37. 37.The two interior opposite angles of a triangle are 55° and 28°. What is the exterior angle (in degrees)?
  38. 38.In a right-angled triangle, one of the other two angles is 17°. What is the third angle (in degrees)?
  39. 39.Can a triangle have sides of 4 cm, 2 cm and 3 cm? (a) No (b) Yes
  40. 40.Can a triangle have sides of 7 cm, 18 cm and 6 cm? (a) Yes (b) No

Answer key

  1. Yes
  2. 10
  3. Yes
  4. 45
  5. 27
  6. 90
  7. 34
  8. 53
  9. 87
  10. 40
  11. 55
  12. Yes
  13. 58
  14. 93
  15. 24
  16. 128
  17. 43
  18. Yes
  19. 42
  20. 90
  21. 25
  22. 7
  23. 25
  24. 10
  25. 45
  26. 68
  27. 25
  28. Yes
  29. 36
  30. 38
  31. 100
  32. 118
  33. 78
  34. 61
  35. 72
  36. 8
  37. 83
  38. 73
  39. Yes
  40. No

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