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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 436 · 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.

NameDateTime takenScore ___ / 40
  1. 1.An exterior angle of a triangle is 53°. One of its two interior opposite angles is 25°. What is the other one (in degrees)?
  2. 2.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  3. 3.In a right-angled triangle, one of the other two angles is 46°. What is the third angle (in degrees)?
  4. 4.An exterior angle of a triangle is 68°. One of its two interior opposite angles is 41°. What is the other one (in degrees)?
  5. 5.An exterior angle of a triangle is 68°. One of its two interior opposite angles is 20°. What is the other one (in degrees)?
  6. 6.In an isosceles triangle, the angle between the two equal sides is 36°. What is each of the other two angles (in degrees)?
  7. 7.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  8. 8.An exterior angle of a triangle is 107°. One of its two interior opposite angles is 61°. What is the other one (in degrees)?
  9. 9.The two interior opposite angles of a triangle are 29° and 34°. What is the exterior angle (in degrees)?
  10. 10.Can a triangle have sides of 4 cm, 3 cm and 7 cm? (a) Yes (b) No
  11. 11.An exterior angle of a triangle is 98°. One of its two interior opposite angles is 22°. What is the other one (in degrees)?
  12. 12.The two interior opposite angles of a triangle are 78° and 40°. What is the exterior angle (in degrees)?
  13. 13.Can a triangle have sides of 24 cm, 11 cm and 9 cm? (a) Yes (b) No
  14. 14.An exterior angle of a triangle is 61°. One of its two interior opposite angles is 31°. What is the other one (in degrees)?
  15. 15.Can a triangle have sides of 5 cm, 12 cm and 6 cm? (a) No (b) Yes
  16. 16.Can a triangle have sides of 15 cm, 4 cm and 7 cm? (a) Yes (b) No
  17. 17.The two interior opposite angles of a triangle are 54° and 79°. What is the exterior angle (in degrees)?
  18. 18.In an isosceles triangle, the two equal angles are 25° each. What is the third angle (in degrees)?
  19. 19.In triangle ABC, angle A = 76° and angle B = 34°. What is angle C (in degrees)?
  20. 20.In triangle ABC, angle A = 52° and angle B = 93°. What is angle C (in degrees)?
  21. 21.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  22. 22.Can a triangle have sides of 10 cm, 22 cm and 10 cm? (a) No (b) Yes
  23. 23.In an isosceles triangle, the angle between the two equal sides is 88°. What is each of the other two angles (in degrees)?
  24. 24.The longest side of a right-angled triangle is 10 cm and one of the other sides is 8 cm. How long is the third side (in cm)?
  25. 25.An exterior angle of a triangle is 108°. One of its two interior opposite angles is 73°. What is the other one (in degrees)?
  26. 26.The two shorter sides of a right-angled triangle are 5 cm and 12 cm. How long is the longest side (in cm)?
  27. 27.In a right-angled triangle, one of the other two angles is 16°. What is the third angle (in degrees)?
  28. 28.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  29. 29.The two interior opposite angles of a triangle are 50° and 62°. What is the exterior angle (in degrees)?
  30. 30.The two interior opposite angles of a triangle are 27° and 59°. What is the exterior angle (in degrees)?
  31. 31.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  32. 32.An exterior angle of a triangle is 79°. One of its two interior opposite angles is 49°. What is the other one (in degrees)?
  33. 33.Can a triangle have sides of 23 cm, 10 cm and 10 cm? (a) Yes (b) No
  34. 34.In triangle ABC, angle A = 75° and angle B = 41°. What is angle C (in degrees)?
  35. 35.In an isosceles triangle, the two equal angles are 42° each. What is the third angle (in degrees)?
  36. 36.In an isosceles triangle, the two equal angles are 47° each. What is the third angle (in degrees)?
  37. 37.Can a triangle have sides of 17 cm, 9 cm and 3 cm? (a) Yes (b) No
  38. 38.In a right-angled triangle, one of the other two angles is 13°. What is the third angle (in degrees)?
  39. 39.In triangle ABC, angle A = 27° and angle B = 59°. What is angle C (in degrees)?
  40. 40.Can a triangle have sides of 11 cm, 9 cm and 5 cm? (a) No (b) Yes

Answer key

  1. 28
  2. 20
  3. 44
  4. 27
  5. 48
  6. 72
  7. 45
  8. 46
  9. 63
  10. No
  11. 76
  12. 118
  13. No
  14. 30
  15. No
  16. No
  17. 133
  18. 130
  19. 70
  20. 35
  21. 18
  22. No
  23. 46
  24. 6
  25. 35
  26. 13
  27. 74
  28. 25
  29. 112
  30. 86
  31. 90
  32. 30
  33. No
  34. 64
  35. 96
  36. 86
  37. No
  38. 77
  39. 94
  40. Yes

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