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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 336 · 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.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  2. 2.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)?
  3. 3.An exterior angle of a triangle is 97°. One of its two interior opposite angles is 29°. What is the other one (in degrees)?
  4. 4.Can a triangle have sides of 12 cm, 8 cm and 8 cm? (a) Yes (b) No
  5. 5.The angles of a triangle are in the ratio 3 : 5 : 7. What is the biggest angle (in degrees)?
  6. 6.In triangle ABC, angle A = 56° and angle B = 83°. What is angle C (in degrees)?
  7. 7.The two interior opposite angles of a triangle are 69° and 53°. What is the exterior angle (in degrees)?
  8. 8.The two shorter sides of a right-angled triangle are 12 cm and 5 cm. How long is the longest side (in cm)?
  9. 9.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  10. 10.An exterior angle of a triangle is 61°. One of its two interior opposite angles is 40°. What is the other one (in degrees)?
  11. 11.The two interior opposite angles of a triangle are 68° and 72°. What is the exterior angle (in degrees)?
  12. 12.Can a triangle have sides of 10 cm, 6 cm and 10 cm? (a) No (b) Yes
  13. 13.In an isosceles triangle, the two equal angles are 31° each. What is the third angle (in degrees)?
  14. 14.In triangle ABC, angle A = 91° and angle B = 28°. What is angle C (in degrees)?
  15. 15.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  16. 16.The two interior opposite angles of a triangle are 38° and 66°. What is the exterior angle (in degrees)?
  17. 17.An exterior angle of a triangle is 84°. One of its two interior opposite angles is 49°. What is the other one (in degrees)?
  18. 18.The two interior opposite angles of a triangle are 80° and 34°. What is the exterior angle (in degrees)?
  19. 19.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  20. 20.Can a triangle have sides of 9 cm, 9 cm and 3 cm? (a) No (b) Yes
  21. 21.Can a triangle have sides of 10 cm, 21 cm and 12 cm? (a) No (b) Yes
  22. 22.The two shorter sides of a right-angled triangle are 36 cm and 15 cm. How long is the longest side (in cm)?
  23. 23.In an isosceles triangle, the angle between the two equal sides is 56°. What is each of the other two angles (in degrees)?
  24. 24.Can a triangle have sides of 4 cm, 12 cm and 8 cm? (a) No (b) Yes
  25. 25.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)?
  26. 26.In triangle ABC, angle A = 91° and angle B = 30°. What is angle C (in degrees)?
  27. 27.In an isosceles triangle, the two equal angles are 28° each. What is the third angle (in degrees)?
  28. 28.In triangle ABC, angle A = 93° and angle B = 36°. What is angle C (in degrees)?
  29. 29.In an isosceles triangle, the angle between the two equal sides is 52°. What is each of the other two angles (in degrees)?
  30. 30.Can a triangle have sides of 7 cm, 18 cm and 6 cm? (a) Yes (b) No
  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.The two interior opposite angles of a triangle are 40° and 32°. What is the exterior angle (in degrees)?
  33. 33.Can a triangle have sides of 9 cm, 21 cm and 8 cm? (a) No (b) Yes
  34. 34.Can a triangle have sides of 4 cm, 4 cm and 5 cm? (a) No (b) Yes
  35. 35.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (in degrees)?
  36. 36.In an isosceles triangle, the angle between the two equal sides is 150°. What is each of the other two angles (in degrees)?
  37. 37.An exterior angle of a triangle is 135°. One of its two interior opposite angles is 63°. What is the other one (in degrees)?
  38. 38.In triangle ABC, angle A = 46° and angle B = 78°. What is angle C (in degrees)?
  39. 39.In a right-angled triangle, one of the other two angles is 35°. What is the third angle (in degrees)?
  40. 40.An exterior angle of a triangle is 129°. One of its two interior opposite angles is 80°. What is the other one (in degrees)?

Answer key

  1. 17
  2. 6
  3. 68
  4. Yes
  5. 84
  6. 41
  7. 122
  8. 13
  9. 90
  10. 21
  11. 140
  12. Yes
  13. 118
  14. 61
  15. 75
  16. 104
  17. 35
  18. 114
  19. 20
  20. Yes
  21. Yes
  22. 39
  23. 62
  24. No
  25. 15
  26. 59
  27. 124
  28. 51
  29. 64
  30. No
  31. 24
  32. 72
  33. No
  34. Yes
  35. 72
  36. 15
  37. 72
  38. 56
  39. 55
  40. 49

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