← Triangles: angle sum, exterior angle and Pythagoras lesson New set →

Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 470 · 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 7 cm, 6 cm and 12 cm? (a) No (b) Yes
  2. 2.In triangle ABC, angle A = 76° and angle B = 29°. What is angle C (in degrees)?
  3. 3.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  4. 4.In triangle ABC, angle A = 29° and angle B = 50°. What is angle C (in degrees)?
  5. 5.In triangle ABC, angle A = 66° and angle B = 62°. What is angle C (in degrees)?
  6. 6.In a right-angled triangle, one of the other two angles is 46°. What is the third angle (in degrees)?
  7. 7.The two shorter sides of a right-angled triangle are 12 cm and 16 cm. How long is the longest side (in cm)?
  8. 8.The angles of a triangle are in the ratio 5 : 6 : 7. What is the biggest angle (in degrees)?
  9. 9.In triangle ABC, angle A = 26° and angle B = 98°. What is angle C (in degrees)?
  10. 10.The longest side of a right-angled triangle is 13 cm and one of the other sides is 12 cm. How long is the third side (in cm)?
  11. 11.In a right-angled triangle, one of the other two angles is 24°. What is the third angle (in degrees)?
  12. 12.Can a triangle have sides of 8 cm, 8 cm and 4 cm? (a) No (b) Yes
  13. 13.Can a triangle have sides of 15 cm, 11 cm and 3 cm? (a) No (b) Yes
  14. 14.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  15. 15.In triangle ABC, angle A = 74° and angle B = 38°. What is angle C (in degrees)?
  16. 16.The two shorter sides of a right-angled triangle are 5 cm and 12 cm. How long is the longest side (in cm)?
  17. 17.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  18. 18.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  19. 19.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)?
  20. 20.The two interior opposite angles of a triangle are 29° and 58°. What is the exterior angle (in degrees)?
  21. 21.The longest side of a right-angled triangle is 25 cm and one of the other sides is 20 cm. How long is the third side (in cm)?
  22. 22.In triangle ABC, angle A = 78° and angle B = 60°. What is angle C (in degrees)?
  23. 23.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  24. 24.In an isosceles triangle, the two equal angles are 32° each. What is the third angle (in degrees)?
  25. 25.Can a triangle have sides of 7 cm, 11 cm and 10 cm? (a) No (b) Yes
  26. 26.The longest side of a right-angled triangle is 10 cm and one of the other sides is 6 cm. How long is the third side (in cm)?
  27. 27.In an isosceles triangle, the two equal angles are 21° each. What is the third angle (in degrees)?
  28. 28.In an isosceles triangle, the two equal angles are 37° each. What is the third angle (in degrees)?
  29. 29.In triangle ABC, angle A = 64° and angle B = 40°. What is angle C (in degrees)?
  30. 30.In a right-angled triangle, one of the other two angles is 41°. What is the third angle (in degrees)?
  31. 31.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  32. 32.In an isosceles triangle, the angle between the two equal sides is 72°. What is each of the other two angles (in degrees)?
  33. 33.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  34. 34.The two interior opposite angles of a triangle are 24° and 31°. What is the exterior angle (in degrees)?
  35. 35.In an isosceles triangle, the two equal angles are 74° each. What is the third angle (in degrees)?
  36. 36.Can a triangle have sides of 7 cm, 10 cm and 3 cm? (a) Yes (b) No
  37. 37.An exterior angle of a triangle is 101°. One of its two interior opposite angles is 68°. What is the other one (in degrees)?
  38. 38.In a right-angled triangle, one of the other two angles is 21°. What is the third angle (in degrees)?
  39. 39.In triangle ABC, angle A = 94° and angle B = 37°. What is angle C (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 25°. What is the third angle (in degrees)?

Answer key

  1. Yes
  2. 75
  3. 20
  4. 101
  5. 52
  6. 44
  7. 20
  8. 70
  9. 56
  10. 5
  11. 66
  12. Yes
  13. No
  14. 100
  15. 68
  16. 13
  17. 72
  18. 25
  19. 15
  20. 87
  21. 15
  22. 42
  23. 40
  24. 116
  25. Yes
  26. 8
  27. 138
  28. 106
  29. 76
  30. 49
  31. 17
  32. 54
  33. 17
  34. 55
  35. 32
  36. No
  37. 33
  38. 69
  39. 49
  40. 65

Free maths worksheets lessons, practice and worksheets at talentjr.in/maths-worksheets