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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 496 · 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.In an isosceles triangle, the two equal angles are 63° each. What is the third angle (in degrees)?
  2. 2.An exterior angle of a triangle is 63°. One of its two interior opposite angles is 21°. What is the other one (in degrees)?
  3. 3.In a right-angled triangle, one of the other two angles is 48°. What is the third angle (in degrees)?
  4. 4.The two interior opposite angles of a triangle are 66° and 58°. What is the exterior angle (in degrees)?
  5. 5.In a right-angled triangle, one of the other two angles is 47°. What is the third angle (in degrees)?
  6. 6.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (in degrees)?
  7. 7.In a right-angled triangle, one of the other two angles is 53°. What is the third angle (in degrees)?
  8. 8.The two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  9. 9.In triangle ABC, angle A = 25° and angle B = 81°. What is angle C (in degrees)?
  10. 10.Can a triangle have sides of 2 cm, 9 cm and 5 cm? (a) Yes (b) No
  11. 11.The angles of a triangle are in the ratio 1 : 2 : 6. What is the smallest angle (in degrees)?
  12. 12.Can a triangle have sides of 2 cm, 4 cm and 2 cm? (a) Yes (b) No
  13. 13.The longest side of a right-angled triangle is 17 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  14. 14.An exterior angle of a triangle is 99°. One of its two interior opposite angles is 40°. What is the other one (in degrees)?
  15. 15.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  16. 16.In a right-angled triangle, one of the other two angles is 52°. What is the third angle (in degrees)?
  17. 17.In triangle ABC, angle A = 57° and angle B = 52°. What is angle C (in degrees)?
  18. 18.The longest side of a right-angled triangle is 30 cm and one of the other sides is 24 cm. How long is the third side (in cm)?
  19. 19.In an isosceles triangle, the angle between the two equal sides is 84°. What is each of the other two angles (in degrees)?
  20. 20.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  21. 21.The two interior opposite angles of a triangle are 45° and 79°. What is the exterior angle (in degrees)?
  22. 22.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  23. 23.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  24. 24.In a right-angled triangle, one of the other two angles is 72°. What is the third angle (in degrees)?
  25. 25.Can a triangle have sides of 10 cm, 10 cm and 10 cm? (a) Yes (b) No
  26. 26.In an isosceles triangle, the two equal angles are 81° each. What is the third angle (in degrees)?
  27. 27.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  28. 28.In an isosceles triangle, the angle between the two equal sides is 122°. What is each of the other two angles (in degrees)?
  29. 29.The two interior opposite angles of a triangle are 76° and 40°. What is the exterior angle (in degrees)?
  30. 30.Can a triangle have sides of 4 cm, 2 cm and 3 cm? (a) No (b) Yes
  31. 31.Can a triangle have sides of 9 cm, 19 cm and 9 cm? (a) Yes (b) No
  32. 32.Can a triangle have sides of 11 cm, 10 cm and 9 cm? (a) No (b) Yes
  33. 33.The two interior opposite angles of a triangle are 51° and 53°. What is the exterior angle (in degrees)?
  34. 34.Can a triangle have sides of 7 cm, 6 cm and 2 cm? (a) Yes (b) No
  35. 35.Can a triangle have sides of 21 cm, 11 cm and 7 cm? (a) Yes (b) No
  36. 36.In an isosceles triangle, the angle between the two equal sides is 26°. What is each of the other two angles (in degrees)?
  37. 37.An exterior angle of a triangle is 84°. One of its two interior opposite angles is 42°. What is the other one (in degrees)?
  38. 38.In triangle ABC, angle A = 70° and angle B = 73°. What is angle C (in degrees)?
  39. 39.The two interior opposite angles of a triangle are 41° and 29°. What is the exterior angle (in degrees)?
  40. 40.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)?

Answer key

  1. 54
  2. 42
  3. 42
  4. 124
  5. 43
  6. 72
  7. 37
  8. 39
  9. 74
  10. No
  11. 20
  12. No
  13. 8
  14. 59
  15. 18
  16. 38
  17. 71
  18. 18
  19. 48
  20. 100
  21. 124
  22. 90
  23. 120
  24. 18
  25. Yes
  26. 18
  27. 17
  28. 29
  29. 116
  30. Yes
  31. No
  32. Yes
  33. 104
  34. Yes
  35. No
  36. 77
  37. 42
  38. 37
  39. 70
  40. 24

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