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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 827 · 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 94°. One of its two interior opposite angles is 72°. What is the other one (in degrees)?
  2. 2.The angles of a triangle are in the ratio 3 : 5 : 7. What is the biggest angle (in degrees)?
  3. 3.In an isosceles triangle, the two equal angles are 33° each. What is the third angle (in degrees)?
  4. 4.Can a triangle have sides of 11 cm, 9 cm and 3 cm? (a) Yes (b) No
  5. 5.Can a triangle have sides of 9 cm, 17 cm and 5 cm? (a) No (b) Yes
  6. 6.The two shorter sides of a right-angled triangle are 12 cm and 9 cm. How long is the longest side (in cm)?
  7. 7.In triangle ABC, angle A = 100° and angle B = 26°. What is angle C (in degrees)?
  8. 8.In triangle ABC, angle A = 26° and angle B = 105°. What is angle C (in degrees)?
  9. 9.Can a triangle have sides of 9 cm, 22 cm and 9 cm? (a) Yes (b) No
  10. 10.In triangle ABC, angle A = 93° and angle B = 41°. What is angle C (in degrees)?
  11. 11.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  12. 12.The two interior opposite angles of a triangle are 32° and 27°. What is the exterior angle (in degrees)?
  13. 13.In a right-angled triangle, one of the other two angles is 57°. What is the third angle (in degrees)?
  14. 14.An exterior angle of a triangle is 125°. One of its two interior opposite angles is 53°. What is the other one (in degrees)?
  15. 15.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  16. 16.The longest side of a right-angled triangle is 20 cm and one of the other sides is 12 cm. How long is the third side (in cm)?
  17. 17.In triangle ABC, angle A = 21° and angle B = 68°. What is angle C (in degrees)?
  18. 18.The longest side of a right-angled triangle is 25 cm and one of the other sides is 24 cm. How long is the third side (in cm)?
  19. 19.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  20. 20.In an isosceles triangle, the angle between the two equal sides is 112°. What is each of the other two angles (in degrees)?
  21. 21.An exterior angle of a triangle is 100°. One of its two interior opposite angles is 65°. What is the other one (in degrees)?
  22. 22.In triangle ABC, angle A = 29° and angle B = 124°. What is angle C (in degrees)?
  23. 23.The longest side of a right-angled triangle is 26 cm and one of the other sides is 10 cm. How long is the third side (in cm)?
  24. 24.An exterior angle of a triangle is 94°. One of its two interior opposite angles is 30°. What is the other one (in degrees)?
  25. 25.Can a triangle have sides of 12 cm, 3 cm and 10 cm? (a) Yes (b) No
  26. 26.In triangle ABC, angle A = 72° and angle B = 25°. What is angle C (in degrees)?
  27. 27.The angles of a triangle are in the ratio 2 : 3 : 5. What is the smallest angle (in degrees)?
  28. 28.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)?
  29. 29.The two interior opposite angles of a triangle are 33° and 78°. What is the exterior angle (in degrees)?
  30. 30.In triangle ABC, angle A = 63° and angle B = 57°. What is angle C (in degrees)?
  31. 31.The angles of a triangle are in the ratio 1 : 2 : 2. What is the biggest angle (in degrees)?
  32. 32.The longest side of a right-angled triangle is 15 cm and one of the other sides is 9 cm. How long is the third side (in cm)?
  33. 33.In a right-angled triangle, one of the other two angles is 11°. What is the third angle (in degrees)?
  34. 34.The angles of a triangle are in the ratio 1 : 1 : 2. What is the smallest angle (in degrees)?
  35. 35.The two interior opposite angles of a triangle are 37° and 35°. What is the exterior angle (in degrees)?
  36. 36.In a right-angled triangle, one of the other two angles is 24°. What is the third angle (in degrees)?
  37. 37.The angles of a triangle are in the ratio 1 : 2 : 3. What is the smallest angle (in degrees)?
  38. 38.In triangle ABC, angle A = 98° and angle B = 26°. What is angle C (in degrees)?
  39. 39.In an isosceles triangle, the two equal angles are 23° each. What is the third angle (in degrees)?
  40. 40.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?

Answer key

  1. 22
  2. 84
  3. 114
  4. Yes
  5. No
  6. 15
  7. 54
  8. 49
  9. No
  10. 46
  11. 45
  12. 59
  13. 33
  14. 72
  15. 90
  16. 16
  17. 91
  18. 7
  19. 25
  20. 34
  21. 35
  22. 27
  23. 24
  24. 64
  25. Yes
  26. 83
  27. 36
  28. 15
  29. 111
  30. 60
  31. 72
  32. 12
  33. 79
  34. 45
  35. 72
  36. 66
  37. 30
  38. 56
  39. 134
  40. 48

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