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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 911 · 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.The two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  2. 2.The two interior opposite angles of a triangle are 28° and 42°. What is the exterior angle (in degrees)?
  3. 3.In triangle ABC, angle A = 23° and angle B = 88°. What is angle C (in degrees)?
  4. 4.An exterior angle of a triangle is 120°. One of its two interior opposite angles is 56°. What is the other one (in degrees)?
  5. 5.In triangle ABC, angle A = 23° and angle B = 52°. What is angle C (in degrees)?
  6. 6.In a right-angled triangle, one of the other two angles is 70°. What is the third angle (in degrees)?
  7. 7.The two interior opposite angles of a triangle are 24° and 76°. What is the exterior angle (in degrees)?
  8. 8.In triangle ABC, angle A = 61° and angle B = 47°. What is angle C (in degrees)?
  9. 9.The longest side of a right-angled triangle is 30 cm and one of the other sides is 24 cm. How long is the third side (in cm)?
  10. 10.An exterior angle of a triangle is 49°. One of its two interior opposite angles is 29°. What is the other one (in degrees)?
  11. 11.The two interior opposite angles of a triangle are 32° and 59°. What is the exterior angle (in degrees)?
  12. 12.An exterior angle of a triangle is 101°. One of its two interior opposite angles is 37°. What is the other one (in degrees)?
  13. 13.In a right-angled triangle, one of the other two angles is 66°. What is the third angle (in degrees)?
  14. 14.In a right-angled triangle, one of the other two angles is 48°. What is the third angle (in degrees)?
  15. 15.In an isosceles triangle, the two equal angles are 44° each. What is the third angle (in degrees)?
  16. 16.In triangle ABC, angle A = 32° and angle B = 73°. What is angle C (in degrees)?
  17. 17.In a right-angled triangle, one of the other two angles is 64°. What is the third angle (in degrees)?
  18. 18.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  19. 19.The two shorter sides of a right-angled triangle are 5 cm and 12 cm. How long is the longest side (in cm)?
  20. 20.In triangle ABC, angle A = 28° and angle B = 93°. What is angle C (in degrees)?
  21. 21.In an isosceles triangle, the angle between the two equal sides is 152°. What is each of the other two angles (in degrees)?
  22. 22.In triangle ABC, angle A = 73° and angle B = 32°. What is angle C (in degrees)?
  23. 23.The angles of a triangle are in the ratio 1 : 2 : 2. What is the biggest angle (in degrees)?
  24. 24.In a right-angled triangle, one of the other two angles is 20°. What is the third angle (in degrees)?
  25. 25.In an isosceles triangle, the two equal angles are 67° each. What is the third angle (in degrees)?
  26. 26.Can a triangle have sides of 8 cm, 9 cm and 2 cm? (a) No (b) Yes
  27. 27.In an isosceles triangle, the two equal angles are 53° each. What is the third angle (in degrees)?
  28. 28.In an isosceles triangle, the angle between the two equal sides is 76°. What is each of the other two angles (in degrees)?
  29. 29.In triangle ABC, angle A = 71° and angle B = 46°. What is angle C (in degrees)?
  30. 30.An exterior angle of a triangle is 147°. One of its two interior opposite angles is 75°. What is the other one (in degrees)?
  31. 31.Can a triangle have sides of 11 cm, 12 cm and 3 cm? (a) No (b) Yes
  32. 32.The angles of a triangle are in the ratio 2 : 2 : 5. What is the smallest angle (in degrees)?
  33. 33.The two interior opposite angles of a triangle are 24° and 74°. What is the exterior angle (in degrees)?
  34. 34.An exterior angle of a triangle is 71°. One of its two interior opposite angles is 35°. What is the other one (in degrees)?
  35. 35.In an isosceles triangle, the angle between the two equal sides is 24°. What is each of the other two angles (in degrees)?
  36. 36.In triangle ABC, angle A = 41° and angle B = 93°. What is angle C (in degrees)?
  37. 37.Can a triangle have sides of 9 cm, 4 cm and 6 cm? (a) No (b) Yes
  38. 38.In triangle ABC, angle A = 25° and angle B = 20°. What is angle C (in degrees)?
  39. 39.An exterior angle of a triangle is 52°. One of its two interior opposite angles is 30°. What is the other one (in degrees)?
  40. 40.Can a triangle have sides of 10 cm, 7 cm and 16 cm? (a) No (b) Yes

Answer key

  1. 39
  2. 70
  3. 69
  4. 64
  5. 105
  6. 20
  7. 100
  8. 72
  9. 18
  10. 20
  11. 91
  12. 64
  13. 24
  14. 42
  15. 92
  16. 75
  17. 26
  18. 20
  19. 13
  20. 59
  21. 14
  22. 75
  23. 72
  24. 70
  25. 46
  26. Yes
  27. 74
  28. 52
  29. 63
  30. 72
  31. Yes
  32. 40
  33. 98
  34. 36
  35. 78
  36. 46
  37. Yes
  38. 135
  39. 22
  40. Yes

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