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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 590 · 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 triangle ABC, angle A = 20° and angle B = 114°. What is angle C (in degrees)?
  2. 2.In a right-angled triangle, one of the other two angles is 14°. What is the third angle (in degrees)?
  3. 3.The two interior opposite angles of a triangle are 27° and 80°. What is the exterior angle (in degrees)?
  4. 4.Can a triangle have sides of 5 cm, 9 cm and 5 cm? (a) No (b) Yes
  5. 5.The longest side of a right-angled triangle is 25 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  6. 6.Can a triangle have sides of 9 cm, 9 cm and 23 cm? (a) No (b) Yes
  7. 7.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  8. 8.In triangle ABC, angle A = 40° and angle B = 65°. What is angle C (in degrees)?
  9. 9.The two shorter sides of a right-angled triangle are 6 cm and 8 cm. How long is the longest side (in cm)?
  10. 10.The two interior opposite angles of a triangle are 23° and 74°. What is the exterior angle (in degrees)?
  11. 11.The two interior opposite angles of a triangle are 46° and 72°. What is the exterior angle (in degrees)?
  12. 12.The two shorter sides of a right-angled triangle are 10 cm and 24 cm. How long is the longest side (in cm)?
  13. 13.In an isosceles triangle, the two equal angles are 35° each. What is the third angle (in degrees)?
  14. 14.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)?
  15. 15.In triangle ABC, angle A = 67° and angle B = 68°. What is angle C (in degrees)?
  16. 16.In triangle ABC, angle A = 61° and angle B = 20°. What is angle C (in degrees)?
  17. 17.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  18. 18.Can a triangle have sides of 10 cm, 5 cm and 4 cm? (a) No (b) Yes
  19. 19.The angles of a triangle are in the ratio 3 : 3 : 4. What is the smallest angle (in degrees)?
  20. 20.Can a triangle have sides of 10 cm, 10 cm and 22 cm? (a) No (b) Yes
  21. 21.In an isosceles triangle, the two equal angles are 38° each. What is the third angle (in degrees)?
  22. 22.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  23. 23.In a right-angled triangle, one of the other two angles is 72°. What is the third angle (in degrees)?
  24. 24.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  25. 25.Can a triangle have sides of 2 cm, 3 cm and 2 cm? (a) No (b) Yes
  26. 26.Can a triangle have sides of 10 cm, 21 cm and 10 cm? (a) Yes (b) No
  27. 27.In triangle ABC, angle A = 39° and angle B = 37°. What is angle C (in degrees)?
  28. 28.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)?
  29. 29.In triangle ABC, angle A = 69° and angle B = 24°. What is angle C (in degrees)?
  30. 30.In an isosceles triangle, the angle between the two equal sides is 114°. What is each of the other two angles (in degrees)?
  31. 31.The longest side of a right-angled triangle is 25 cm and one of the other sides is 7 cm. How long is the third side (in cm)?
  32. 32.In an isosceles triangle, the two equal angles are 31° each. What is the third angle (in degrees)?
  33. 33.In an isosceles triangle, the angle between the two equal sides is 148°. What is each of the other two angles (in degrees)?
  34. 34.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  35. 35.The two interior opposite angles of a triangle are 32° and 37°. What is the exterior angle (in degrees)?
  36. 36.In an isosceles triangle, the two equal angles are 76° each. What is the third angle (in degrees)?
  37. 37.In triangle ABC, angle A = 66° and angle B = 21°. What is angle C (in degrees)?
  38. 38.The two interior opposite angles of a triangle are 35° and 27°. What is the exterior angle (in degrees)?
  39. 39.The two interior opposite angles of a triangle are 56° and 45°. What is the exterior angle (in degrees)?
  40. 40.In an isosceles triangle, the angle between the two equal sides is 98°. What is each of the other two angles (in degrees)?

Answer key

  1. 46
  2. 76
  3. 107
  4. Yes
  5. 20
  6. No
  7. 17
  8. 75
  9. 10
  10. 97
  11. 118
  12. 26
  13. 110
  14. 15
  15. 45
  16. 99
  17. 90
  18. No
  19. 54
  20. No
  21. 104
  22. 18
  23. 18
  24. 100
  25. Yes
  26. No
  27. 104
  28. 8
  29. 87
  30. 33
  31. 24
  32. 118
  33. 16
  34. 75
  35. 69
  36. 28
  37. 93
  38. 62
  39. 101
  40. 41

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