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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 529 · 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 two equal angles are 63° each. What is the third angle (in degrees)?
  2. 2.Can a triangle have sides of 12 cm, 4 cm and 19 cm? (a) No (b) Yes
  3. 3.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  4. 4.Can a triangle have sides of 12 cm, 18 cm and 6 cm? (a) No (b) Yes
  5. 5.In an isosceles triangle, the two equal angles are 23° each. What is the third angle (in degrees)?
  6. 6.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  7. 7.The angles of a triangle are in the ratio 1 : 2 : 6. What is the smallest angle (in degrees)?
  8. 8.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)?
  9. 9.The two interior opposite angles of a triangle are 26° and 42°. What is the exterior angle (in degrees)?
  10. 10.An exterior angle of a triangle is 52°. One of its two interior opposite angles is 32°. What is the other one (in degrees)?
  11. 11.In a right-angled triangle, one of the other two angles is 62°. What is the third angle (in degrees)?
  12. 12.In a right-angled triangle, one of the other two angles is 14°. What is the third angle (in degrees)?
  13. 13.Can a triangle have sides of 5 cm, 2 cm and 8 cm? (a) Yes (b) No
  14. 14.In triangle ABC, angle A = 90° and angle B = 64°. What is angle C (in degrees)?
  15. 15.In an isosceles triangle, the angle between the two equal sides is 68°. What is each of the other two angles (in degrees)?
  16. 16.The two shorter sides of a right-angled triangle are 8 cm and 6 cm. How long is the longest side (in cm)?
  17. 17.In a right-angled triangle, one of the other two angles is 57°. What is the third angle (in degrees)?
  18. 18.The angles of a triangle are in the ratio 1 : 2 : 3. What is the smallest angle (in degrees)?
  19. 19.In triangle ABC, angle A = 71° and angle B = 45°. What is angle C (in degrees)?
  20. 20.In triangle ABC, angle A = 60° and angle B = 91°. What is angle C (in degrees)?
  21. 21.In an isosceles triangle, the angle between the two equal sides is 144°. What is each of the other two angles (in degrees)?
  22. 22.In an isosceles triangle, the two equal angles are 72° each. What is the third angle (in degrees)?
  23. 23.In a right-angled triangle, one of the other two angles is 78°. What is the third angle (in degrees)?
  24. 24.Can a triangle have sides of 7 cm, 19 cm and 12 cm? (a) No (b) Yes
  25. 25.In an isosceles triangle, the angle between the two equal sides is 46°. What is each of the other two angles (in degrees)?
  26. 26.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  27. 27.In an isosceles triangle, the angle between the two equal sides is 44°. What is each of the other two angles (in degrees)?
  28. 28.The two interior opposite angles of a triangle are 62° and 76°. What is the exterior angle (in degrees)?
  29. 29.In an isosceles triangle, the angle between the two equal sides is 28°. What is each of the other two angles (in degrees)?
  30. 30.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?
  31. 31.An exterior angle of a triangle is 139°. One of its two interior opposite angles is 61°. What is the other one (in degrees)?
  32. 32.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  33. 33.Can a triangle have sides of 8 cm, 17 cm and 8 cm? (a) Yes (b) No
  34. 34.Can a triangle have sides of 12 cm, 4 cm and 10 cm? (a) Yes (b) No
  35. 35.In a right-angled triangle, one of the other two angles is 59°. What is the third angle (in degrees)?
  36. 36.In triangle ABC, angle A = 30° and angle B = 71°. What is angle C (in degrees)?
  37. 37.In triangle ABC, angle A = 51° and angle B = 56°. What is angle C (in degrees)?
  38. 38.In an isosceles triangle, the angle between the two equal sides is 90°. What is each of the other two angles (in degrees)?
  39. 39.In an isosceles triangle, the angle between the two equal sides is 130°. What is each of the other two angles (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 26°. What is the third angle (in degrees)?

Answer key

  1. 54
  2. No
  3. 36
  4. No
  5. 134
  6. 45
  7. 20
  8. 15
  9. 68
  10. 20
  11. 28
  12. 76
  13. No
  14. 26
  15. 56
  16. 10
  17. 33
  18. 30
  19. 64
  20. 29
  21. 18
  22. 36
  23. 12
  24. No
  25. 67
  26. 20
  27. 68
  28. 138
  29. 76
  30. 50
  31. 78
  32. 25
  33. No
  34. Yes
  35. 31
  36. 79
  37. 73
  38. 45
  39. 25
  40. 64

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