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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 906 · 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 26°. What is each of the other two angles (in degrees)?
  2. 2.Can a triangle have sides of 4 cm, 3 cm and 4 cm? (a) Yes (b) No
  3. 3.In an isosceles triangle, the angle between the two equal sides is 48°. What is each of the other two angles (in degrees)?
  4. 4.The angles of a triangle are in the ratio 2 : 3 : 5. What is the smallest angle (in degrees)?
  5. 5.The angles of a triangle are in the ratio 1 : 2 : 3. What is the biggest angle (in degrees)?
  6. 6.The two interior opposite angles of a triangle are 78° and 24°. What is the exterior angle (in degrees)?
  7. 7.In an isosceles triangle, the two equal angles are 34° each. What is the third angle (in degrees)?
  8. 8.An exterior angle of a triangle is 114°. One of its two interior opposite angles is 44°. What is the other one (in degrees)?
  9. 9.In triangle ABC, angle A = 99° and angle B = 53°. What is angle C (in degrees)?
  10. 10.In triangle ABC, angle A = 49° and angle B = 91°. What is angle C (in degrees)?
  11. 11.In triangle ABC, angle A = 69° and angle B = 70°. What is angle C (in degrees)?
  12. 12.In a right-angled triangle, one of the other two angles is 25°. What is the third angle (in degrees)?
  13. 13.An exterior angle of a triangle is 141°. One of its two interior opposite angles is 72°. What is the other one (in degrees)?
  14. 14.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  15. 15.In an isosceles triangle, the angle between the two equal sides is 56°. What is each of the other two angles (in degrees)?
  16. 16.An exterior angle of a triangle is 95°. One of its two interior opposite angles is 60°. What is the other one (in degrees)?
  17. 17.In triangle ABC, angle A = 21° and angle B = 54°. 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 15 cm. How long is the third side (in cm)?
  19. 19.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (in degrees)?
  20. 20.In triangle ABC, angle A = 29° and angle B = 71°. What is angle C (in degrees)?
  21. 21.In a right-angled triangle, one of the other two angles is 10°. What is the third angle (in degrees)?
  22. 22.In triangle ABC, angle A = 91° and angle B = 38°. What is angle C (in degrees)?
  23. 23.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  24. 24.In triangle ABC, angle A = 33° and angle B = 107°. What is angle C (in degrees)?
  25. 25.In an isosceles triangle, the angle between the two equal sides is 42°. What is each of the other two angles (in degrees)?
  26. 26.In an isosceles triangle, the two equal angles are 81° each. What is the third angle (in degrees)?
  27. 27.In a right-angled triangle, one of the other two angles is 38°. What is the third angle (in degrees)?
  28. 28.In triangle ABC, angle A = 43° and angle B = 114°. What is angle C (in degrees)?
  29. 29.Can a triangle have sides of 10 cm, 10 cm and 24 cm? (a) Yes (b) No
  30. 30.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)?
  31. 31.Can a triangle have sides of 12 cm, 11 cm and 10 cm? (a) No (b) Yes
  32. 32.In a right-angled triangle, one of the other two angles is 30°. What is the third angle (in degrees)?
  33. 33.In triangle ABC, angle A = 74° and angle B = 58°. What is angle C (in degrees)?
  34. 34.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  35. 35.Can a triangle have sides of 15 cm, 9 cm and 3 cm? (a) Yes (b) No
  36. 36.In an isosceles triangle, the angle between the two equal sides is 92°. What is each of the other two angles (in degrees)?
  37. 37.The two interior opposite angles of a triangle are 64° and 43°. What is the exterior angle (in degrees)?
  38. 38.Can a triangle have sides of 8 cm, 7 cm and 9 cm? (a) Yes (b) No
  39. 39.In a right-angled triangle, one of the other two angles is 35°. What is the third angle (in degrees)?
  40. 40.In an isosceles triangle, the angle between the two equal sides is 142°. What is each of the other two angles (in degrees)?

Answer key

  1. 77
  2. Yes
  3. 66
  4. 36
  5. 90
  6. 102
  7. 112
  8. 70
  9. 28
  10. 40
  11. 41
  12. 65
  13. 69
  14. 36
  15. 62
  16. 35
  17. 105
  18. 8
  19. 72
  20. 80
  21. 80
  22. 51
  23. 17
  24. 40
  25. 69
  26. 18
  27. 52
  28. 23
  29. No
  30. 3
  31. Yes
  32. 60
  33. 48
  34. 25
  35. No
  36. 44
  37. 107
  38. Yes
  39. 55
  40. 19

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