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Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 686 · 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.An exterior angle of a triangle is 63°. One of its two interior opposite angles is 33°. What is the other one (in degrees)?
  2. 2.Can a triangle have sides of 4 cm, 3 cm and 8 cm? (a) Yes (b) No
  3. 3.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  4. 4.In triangle ABC, angle A = 76° and angle B = 64°. What is angle C (in degrees)?
  5. 5.Can a triangle have sides of 19 cm, 9 cm and 7 cm? (a) Yes (b) No
  6. 6.In a right-angled triangle, one of the other two angles is 57°. What is the third angle (in degrees)?
  7. 7.The two interior opposite angles of a triangle are 34° and 64°. What is the exterior angle (in degrees)?
  8. 8.In triangle ABC, angle A = 96° and angle B = 26°. What is angle C (in degrees)?
  9. 9.The two shorter sides of a right-angled triangle are 24 cm and 10 cm. How long is the longest side (in cm)?
  10. 10.In an isosceles triangle, the angle between the two equal sides is 64°. What is each of the other two angles (in degrees)?
  11. 11.Can a triangle have sides of 8 cm, 2 cm and 10 cm? (a) Yes (b) No
  12. 12.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)?
  13. 13.The two interior opposite angles of a triangle are 23° and 55°. What is the exterior angle (in degrees)?
  14. 14.In an isosceles triangle, the two equal angles are 56° each. What is the third angle (in degrees)?
  15. 15.In triangle ABC, angle A = 69° and angle B = 55°. What is angle C (in degrees)?
  16. 16.An exterior angle of a triangle is 96°. One of its two interior opposite angles is 21°. What is the other one (in degrees)?
  17. 17.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  18. 18.The angles of a triangle are in the ratio 1 : 2 : 2. What is the smallest angle (in degrees)?
  19. 19.The two shorter sides of a right-angled triangle are 6 cm and 8 cm. How long is the longest side (in cm)?
  20. 20.In a right-angled triangle, one of the other two angles is 48°. What is the third angle (in degrees)?
  21. 21.In an isosceles triangle, the angle between the two equal sides is 158°. What is each of the other two angles (in degrees)?
  22. 22.The two interior opposite angles of a triangle are 70° and 48°. What is the exterior angle (in degrees)?
  23. 23.In an isosceles triangle, the two equal angles are 21° each. What is the third angle (in degrees)?
  24. 24.Can a triangle have sides of 2 cm, 12 cm and 5 cm? (a) No (b) Yes
  25. 25.In an isosceles triangle, the two equal angles are 52° each. What is the third angle (in degrees)?
  26. 26.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)?
  27. 27.In an isosceles triangle, the two equal angles are 47° each. What is the third angle (in degrees)?
  28. 28.In an isosceles triangle, the angle between the two equal sides is 62°. What is each of the other two angles (in degrees)?
  29. 29.The two interior opposite angles of a triangle are 27° and 61°. What is the exterior angle (in degrees)?
  30. 30.Can a triangle have sides of 19 cm, 4 cm and 12 cm? (a) Yes (b) No
  31. 31.In triangle ABC, angle A = 100° and angle B = 48°. What is angle C (in degrees)?
  32. 32.In an isosceles triangle, the two equal angles are 30° each. What is the third angle (in degrees)?
  33. 33.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)?
  34. 34.Can a triangle have sides of 11 cm, 8 cm and 24 cm? (a) Yes (b) No
  35. 35.In an isosceles triangle, the angle between the two equal sides is 116°. What is each of the other two angles (in degrees)?
  36. 36.In a right-angled triangle, one of the other two angles is 44°. What is the third angle (in degrees)?
  37. 37.In triangle ABC, angle A = 48° and angle B = 51°. What is angle C (in degrees)?
  38. 38.In a right-angled triangle, one of the other two angles is 30°. What is the third angle (in degrees)?
  39. 39.The two interior opposite angles of a triangle are 25° and 25°. What is the exterior angle (in degrees)?
  40. 40.Can a triangle have sides of 16 cm, 4 cm and 12 cm? (a) No (b) Yes

Answer key

  1. 30
  2. No
  3. 17
  4. 40
  5. No
  6. 33
  7. 98
  8. 58
  9. 26
  10. 58
  11. No
  12. 7
  13. 78
  14. 68
  15. 56
  16. 75
  17. 75
  18. 36
  19. 10
  20. 42
  21. 11
  22. 118
  23. 138
  24. No
  25. 76
  26. 12
  27. 86
  28. 59
  29. 88
  30. No
  31. 32
  32. 120
  33. 8
  34. No
  35. 32
  36. 46
  37. 81
  38. 60
  39. 50
  40. No

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