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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 116 · 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.Can a triangle have sides of 9 cm, 3 cm and 14 cm? (a) Yes (b) No
  2. 2.In a right-angled triangle, one of the other two angles is 36°. What is the third angle (in degrees)?
  3. 3.In triangle ABC, angle A = 44° and angle B = 97°. What is angle C (in degrees)?
  4. 4.In a right-angled triangle, one of the other two angles is 32°. What is the third angle (in degrees)?
  5. 5.The two shorter sides of a right-angled triangle are 24 cm and 10 cm. How long is the longest side (in cm)?
  6. 6.In an isosceles triangle, the angle between the two equal sides is 114°. What is each of the other two angles (in degrees)?
  7. 7.The longest side of a right-angled triangle is 5 cm and one of the other sides is 3 cm. How long is the third side (in cm)?
  8. 8.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  9. 9.Can a triangle have sides of 7 cm, 8 cm and 12 cm? (a) No (b) Yes
  10. 10.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)?
  11. 11.In triangle ABC, angle A = 37° and angle B = 121°. What is angle C (in degrees)?
  12. 12.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  13. 13.Can a triangle have sides of 21 cm, 11 cm and 9 cm? (a) Yes (b) No
  14. 14.In triangle ABC, angle A = 98° and angle B = 38°. What is angle C (in degrees)?
  15. 15.In a right-angled triangle, one of the other two angles is 17°. What is the third angle (in degrees)?
  16. 16.In triangle ABC, angle A = 49° and angle B = 86°. What is angle C (in degrees)?
  17. 17.The two interior opposite angles of a triangle are 34° and 20°. What is the exterior angle (in degrees)?
  18. 18.The two interior opposite angles of a triangle are 64° and 66°. What is the exterior angle (in degrees)?
  19. 19.In a right-angled triangle, one of the other two angles is 10°. What is the third angle (in degrees)?
  20. 20.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  21. 21.Can a triangle have sides of 11 cm, 19 cm and 7 cm? (a) No (b) Yes
  22. 22.In a right-angled triangle, one of the other two angles is 44°. What is the third angle (in degrees)?
  23. 23.In triangle ABC, angle A = 29° and angle B = 29°. What is angle C (in degrees)?
  24. 24.In a right-angled triangle, one of the other two angles is 74°. What is the third angle (in degrees)?
  25. 25.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  26. 26.In a right-angled triangle, one of the other two angles is 11°. What is the third angle (in degrees)?
  27. 27.An exterior angle of a triangle is 57°. One of its two interior opposite angles is 31°. What is the other one (in degrees)?
  28. 28.In a right-angled triangle, one of the other two angles is 60°. What is the third angle (in degrees)?
  29. 29.The two interior opposite angles of a triangle are 47° and 73°. What is the exterior angle (in degrees)?
  30. 30.In triangle ABC, angle A = 23° and angle B = 131°. What is angle C (in degrees)?
  31. 31.The two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  32. 32.In an isosceles triangle, the two equal angles are 30° each. What is the third angle (in degrees)?
  33. 33.An exterior angle of a triangle is 95°. One of its two interior opposite angles is 74°. 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.In a right-angled triangle, one of the other two angles is 16°. What is the third angle (in degrees)?
  36. 36.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)?
  37. 37.In triangle ABC, angle A = 57° and angle B = 35°. What is angle C (in degrees)?
  38. 38.In an isosceles triangle, the two equal angles are 74° each. What is the third angle (in degrees)?
  39. 39.In a right-angled triangle, one of the other two angles is 25°. What is the third angle (in degrees)?
  40. 40.The longest side of a right-angled triangle is 26 cm and one of the other sides is 24 cm. How long is the third side (in cm)?

Answer key

  1. No
  2. 54
  3. 39
  4. 58
  5. 26
  6. 33
  7. 4
  8. 17
  9. Yes
  10. 8
  11. 22
  12. 90
  13. No
  14. 44
  15. 73
  16. 45
  17. 54
  18. 130
  19. 80
  20. 25
  21. No
  22. 46
  23. 122
  24. 16
  25. 80
  26. 79
  27. 26
  28. 30
  29. 120
  30. 26
  31. 39
  32. 120
  33. 21
  34. 36
  35. 74
  36. 24
  37. 88
  38. 32
  39. 65
  40. 10

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