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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 184 · 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.In an isosceles triangle, the angle between the two equal sides is 56°. What is each of the other two angles (in degrees)?
  2. 2.In a right-angled triangle, one of the other two angles is 19°. What is the third angle (in degrees)?
  3. 3.In an isosceles triangle, the angle between the two equal sides is 108°. What is each of the other two angles (in degrees)?
  4. 4.The angles of a triangle are in the ratio 1 : 1 : 2. What is the smallest angle (in degrees)?
  5. 5.In an isosceles triangle, the angle between the two equal sides is 22°. What is each of the other two angles (in degrees)?
  6. 6.The two interior opposite angles of a triangle are 29° and 20°. What is the exterior angle (in degrees)?
  7. 7.In triangle ABC, angle A = 45° and angle B = 43°. What is angle C (in degrees)?
  8. 8.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  9. 9.In a right-angled triangle, one of the other two angles is 70°. What is the third angle (in degrees)?
  10. 10.In triangle ABC, angle A = 54° and angle B = 88°. What is angle C (in degrees)?
  11. 11.Can a triangle have sides of 6 cm, 7 cm and 11 cm? (a) Yes (b) No
  12. 12.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  13. 13.The two interior opposite angles of a triangle are 33° and 29°. What is the exterior angle (in degrees)?
  14. 14.Can a triangle have sides of 9 cm, 23 cm and 11 cm? (a) Yes (b) No
  15. 15.Can a triangle have sides of 2 cm, 11 cm and 9 cm? (a) Yes (b) No
  16. 16.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  17. 17.In triangle ABC, angle A = 98° and angle B = 22°. What is angle C (in degrees)?
  18. 18.In an isosceles triangle, the two equal angles are 57° each. What is the third angle (in degrees)?
  19. 19.The two interior opposite angles of a triangle are 22° and 26°. What is the exterior angle (in degrees)?
  20. 20.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  21. 21.An exterior angle of a triangle is 83°. One of its two interior opposite angles is 27°. What is the other one (in degrees)?
  22. 22.Can a triangle have sides of 9 cm, 8 cm and 18 cm? (a) No (b) Yes
  23. 23.In an isosceles triangle, the two equal angles are 52° each. What is the third angle (in degrees)?
  24. 24.An exterior angle of a triangle is 107°. One of its two interior opposite angles is 68°. What is the other one (in degrees)?
  25. 25.The two interior opposite angles of a triangle are 60° and 41°. What is the exterior angle (in degrees)?
  26. 26.The two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  27. 27.In an isosceles triangle, the two equal angles are 85° each. What is the third angle (in degrees)?
  28. 28.The longest side of a right-angled triangle is 39 cm and one of the other sides is 36 cm. How long is the third side (in cm)?
  29. 29.In triangle ABC, angle A = 46° and angle B = 85°. What is angle C (in degrees)?
  30. 30.Can a triangle have sides of 4 cm, 9 cm and 9 cm? (a) Yes (b) No
  31. 31.The longest side of a right-angled triangle is 10 cm and one of the other sides is 6 cm. How long is the third side (in cm)?
  32. 32.In a right-angled triangle, one of the other two angles is 37°. What is the third angle (in degrees)?
  33. 33.In an isosceles triangle, the two equal angles are 80° each. What is the third angle (in degrees)?
  34. 34.The two interior opposite angles of a triangle are 57° and 75°. What is the exterior angle (in degrees)?
  35. 35.The two interior opposite angles of a triangle are 40° and 69°. What is the exterior angle (in degrees)?
  36. 36.The angles of a triangle are in the ratio 2 : 2 : 5. What is the smallest angle (in degrees)?
  37. 37.An exterior angle of a triangle is 111°. One of its two interior opposite angles is 38°. What is the other one (in degrees)?
  38. 38.The longest side of a right-angled triangle is 20 cm and one of the other sides is 16 cm. How long is the third side (in cm)?
  39. 39.The two shorter sides of a right-angled triangle are 10 cm and 24 cm. How long is the longest side (in cm)?
  40. 40.Can a triangle have sides of 9 cm, 2 cm and 5 cm? (a) No (b) Yes

Answer key

  1. 62
  2. 71
  3. 36
  4. 45
  5. 79
  6. 49
  7. 92
  8. 25
  9. 20
  10. 38
  11. Yes
  12. 17
  13. 62
  14. No
  15. No
  16. 45
  17. 60
  18. 66
  19. 48
  20. 20
  21. 56
  22. No
  23. 76
  24. 39
  25. 101
  26. 39
  27. 10
  28. 15
  29. 49
  30. Yes
  31. 8
  32. 53
  33. 20
  34. 132
  35. 109
  36. 40
  37. 73
  38. 12
  39. 26
  40. No

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