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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 190 · 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.In an isosceles triangle, the angle between the two equal sides is 72°. What is each of the other two angles (in degrees)?
  2. 2.An exterior angle of a triangle is 120°. One of its two interior opposite angles is 72°. What is the other one (in degrees)?
  3. 3.Can a triangle have sides of 3 cm, 2 cm and 10 cm? (a) Yes (b) No
  4. 4.In a right-angled triangle, one of the other two angles is 63°. What is the third angle (in degrees)?
  5. 5.In triangle ABC, angle A = 73° and angle B = 41°. What is angle C (in degrees)?
  6. 6.In an isosceles triangle, the two equal angles are 40° each. What is the third angle (in degrees)?
  7. 7.In an isosceles triangle, the angle between the two equal sides is 22°. What is each of the other two angles (in degrees)?
  8. 8.In a right-angled triangle, one of the other two angles is 11°. What is the third angle (in degrees)?
  9. 9.The longest side of a right-angled triangle is 13 cm and one of the other sides is 5 cm. How long is the third side (in cm)?
  10. 10.In triangle ABC, angle A = 64° and angle B = 62°. What is angle C (in degrees)?
  11. 11.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  12. 12.In an isosceles triangle, the two equal angles are 35° each. What is the third angle (in degrees)?
  13. 13.Can a triangle have sides of 12 cm, 10 cm and 11 cm? (a) Yes (b) No
  14. 14.The angles of a triangle are in the ratio 1 : 2 : 3. What is the smallest angle (in degrees)?
  15. 15.In triangle ABC, angle A = 49° and angle B = 46°. What is angle C (in degrees)?
  16. 16.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  17. 17.In a right-angled triangle, one of the other two angles is 68°. What is the third angle (in degrees)?
  18. 18.The two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  19. 19.In an isosceles triangle, the two equal angles are 59° each. What is the third angle (in degrees)?
  20. 20.In a right-angled triangle, one of the other two angles is 44°. What is the third angle (in degrees)?
  21. 21.The two interior opposite angles of a triangle are 52° and 43°. What is the exterior angle (in degrees)?
  22. 22.In an isosceles triangle, the two equal angles are 48° each. What is the third angle (in degrees)?
  23. 23.The two interior opposite angles of a triangle are 40° and 40°. What is the exterior angle (in degrees)?
  24. 24.An exterior angle of a triangle is 145°. One of its two interior opposite angles is 73°. What is the other one (in degrees)?
  25. 25.In a right-angled triangle, one of the other two angles is 18°. What is the third angle (in degrees)?
  26. 26.In triangle ABC, angle A = 23° and angle B = 94°. What is angle C (in degrees)?
  27. 27.In triangle ABC, angle A = 21° and angle B = 128°. What is angle C (in degrees)?
  28. 28.Can a triangle have sides of 6 cm, 14 cm and 6 cm? (a) No (b) Yes
  29. 29.In triangle ABC, angle A = 88° and angle B = 49°. What is angle C (in degrees)?
  30. 30.In triangle ABC, angle A = 40° and angle B = 40°. What is angle C (in degrees)?
  31. 31.Can a triangle have sides of 6 cm, 2 cm and 13 cm? (a) No (b) Yes
  32. 32.In an isosceles triangle, the two equal angles are 73° each. What is the third angle (in degrees)?
  33. 33.An exterior angle of a triangle is 108°. One of its two interior opposite angles is 35°. What is the other one (in degrees)?
  34. 34.The longest side of a right-angled triangle is 39 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  35. 35.The angles of a triangle are in the ratio 1 : 2 : 6. What is the smallest angle (in degrees)?
  36. 36.The longest side of a right-angled triangle is 30 cm and one of the other sides is 18 cm. How long is the third side (in cm)?
  37. 37.The longest side of a right-angled triangle is 25 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  38. 38.Can a triangle have sides of 11 cm, 9 cm and 3 cm? (a) No (b) Yes
  39. 39.The two interior opposite angles of a triangle are 69° and 57°. What is the exterior angle (in degrees)?
  40. 40.In triangle ABC, angle A = 75° and angle B = 50°. What is angle C (in degrees)?

Answer key

  1. 54
  2. 48
  3. No
  4. 27
  5. 66
  6. 100
  7. 79
  8. 79
  9. 12
  10. 54
  11. 25
  12. 110
  13. Yes
  14. 30
  15. 85
  16. 90
  17. 22
  18. 39
  19. 62
  20. 46
  21. 95
  22. 84
  23. 80
  24. 72
  25. 72
  26. 63
  27. 31
  28. No
  29. 43
  30. 100
  31. No
  32. 34
  33. 73
  34. 36
  35. 20
  36. 24
  37. 20
  38. Yes
  39. 126
  40. 55

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