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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 339 · 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 interior opposite angles of a triangle are 67° and 46°. What is the exterior angle (in degrees)?
  2. 2.An exterior angle of a triangle is 126°. One of its two interior opposite angles is 71°. What is the other one (in degrees)?
  3. 3.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  4. 4.In a right-angled triangle, one of the other two angles is 69°. What is the third angle (in degrees)?
  5. 5.In a right-angled triangle, one of the other two angles is 79°. What is the third angle (in degrees)?
  6. 6.Can a triangle have sides of 5 cm, 2 cm and 2 cm? (a) No (b) Yes
  7. 7.An exterior angle of a triangle is 121°. One of its two interior opposite angles is 66°. What is the other one (in degrees)?
  8. 8.In an isosceles triangle, the angle between the two equal sides is 156°. What is each of the other two angles (in degrees)?
  9. 9.The two shorter sides of a right-angled triangle are 12 cm and 5 cm. How long is the longest side (in cm)?
  10. 10.The angles of a triangle are in the ratio 1 : 2 : 2. What is the smallest angle (in degrees)?
  11. 11.In triangle ABC, angle A = 31° and angle B = 124°. What is angle C (in degrees)?
  12. 12.In triangle ABC, angle A = 63° and angle B = 59°. What is angle C (in degrees)?
  13. 13.An exterior angle of a triangle is 143°. One of its two interior opposite angles is 72°. What is the other one (in degrees)?
  14. 14.In an isosceles triangle, the angle between the two equal sides is 62°. What is each of the other two angles (in degrees)?
  15. 15.In a right-angled triangle, one of the other two angles is 31°. What is the third angle (in degrees)?
  16. 16.Can a triangle have sides of 19 cm, 3 cm and 12 cm? (a) No (b) Yes
  17. 17.The two shorter sides of a right-angled triangle are 12 cm and 9 cm. How long is the longest side (in cm)?
  18. 18.The two interior opposite angles of a triangle are 47° and 55°. What is the exterior angle (in degrees)?
  19. 19.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)?
  20. 20.In an isosceles triangle, the two equal angles are 59° each. What is the third angle (in degrees)?
  21. 21.In a right-angled triangle, one of the other two angles is 18°. What is the third angle (in degrees)?
  22. 22.An exterior angle of a triangle is 66°. One of its two interior opposite angles is 20°. What is the other one (in degrees)?
  23. 23.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)?
  24. 24.In triangle ABC, angle A = 92° and angle B = 42°. What is angle C (in degrees)?
  25. 25.The two interior opposite angles of a triangle are 55° and 45°. What is the exterior angle (in degrees)?
  26. 26.Can a triangle have sides of 19 cm, 9 cm and 7 cm? (a) No (b) Yes
  27. 27.In triangle ABC, angle A = 27° and angle B = 90°. What is angle C (in degrees)?
  28. 28.Can a triangle have sides of 3 cm, 18 cm and 10 cm? (a) No (b) Yes
  29. 29.In a right-angled triangle, one of the other two angles is 76°. What is the third angle (in degrees)?
  30. 30.Can a triangle have sides of 5 cm, 12 cm and 8 cm? (a) Yes (b) No
  31. 31.In an isosceles triangle, the angle between the two equal sides is 56°. What is each of the other two angles (in degrees)?
  32. 32.In a right-angled triangle, one of the other two angles is 47°. What is the third angle (in degrees)?
  33. 33.Can a triangle have sides of 4 cm, 12 cm and 8 cm? (a) Yes (b) No
  34. 34.The two interior opposite angles of a triangle are 32° and 58°. What is the exterior angle (in degrees)?
  35. 35.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  36. 36.In a right-angled triangle, one of the other two angles is 28°. What is the third angle (in degrees)?
  37. 37.In a right-angled triangle, one of the other two angles is 57°. What is the third angle (in degrees)?
  38. 38.In an isosceles triangle, the two equal angles are 63° each. What is the third angle (in degrees)?
  39. 39.Can a triangle have sides of 9 cm, 4 cm and 15 cm? (a) No (b) Yes
  40. 40.In triangle ABC, angle A = 26° and angle B = 73°. What is angle C (in degrees)?

Answer key

  1. 113
  2. 55
  3. 36
  4. 21
  5. 11
  6. No
  7. 55
  8. 12
  9. 13
  10. 36
  11. 25
  12. 58
  13. 71
  14. 59
  15. 59
  16. No
  17. 15
  18. 102
  19. 7
  20. 62
  21. 72
  22. 46
  23. 24
  24. 46
  25. 100
  26. No
  27. 63
  28. No
  29. 14
  30. Yes
  31. 62
  32. 43
  33. No
  34. 90
  35. 45
  36. 62
  37. 33
  38. 54
  39. No
  40. 81

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