← 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 722 · 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 16 cm, 6 cm and 7 cm? (a) Yes (b) No
  2. 2.The two shorter sides of a right-angled triangle are 20 cm and 15 cm. How long is the longest side (in cm)?
  3. 3.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  4. 4.In triangle ABC, angle A = 23° and angle B = 111°. What is angle C (in degrees)?
  5. 5.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  6. 6.In an isosceles triangle, the two equal angles are 47° each. What is the third angle (in degrees)?
  7. 7.In triangle ABC, angle A = 92° and angle B = 41°. What is angle C (in degrees)?
  8. 8.In a right-angled triangle, one of the other two angles is 51°. What is the third angle (in degrees)?
  9. 9.In a right-angled triangle, one of the other two angles is 18°. What is the third angle (in degrees)?
  10. 10.In an isosceles triangle, the two equal angles are 61° each. What is the third angle (in degrees)?
  11. 11.The longest side of a right-angled triangle is 20 cm and one of the other sides is 16 cm. How long is the third side (in cm)?
  12. 12.In triangle ABC, angle A = 38° and angle B = 108°. What is angle C (in degrees)?
  13. 13.In an isosceles triangle, the angle between the two equal sides is 112°. What is each of the other two angles (in degrees)?
  14. 14.The two interior opposite angles of a triangle are 68° and 64°. What is the exterior angle (in degrees)?
  15. 15.In an isosceles triangle, the angle between the two equal sides is 152°. What is each of the other two angles (in degrees)?
  16. 16.Can a triangle have sides of 11 cm, 18 cm and 6 cm? (a) Yes (b) No
  17. 17.The two interior opposite angles of a triangle are 78° and 71°. What is the exterior angle (in degrees)?
  18. 18.An exterior angle of a triangle is 101°. One of its two interior opposite angles is 31°. What is the other one (in degrees)?
  19. 19.In triangle ABC, angle A = 75° and angle B = 80°. What is angle C (in degrees)?
  20. 20.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  21. 21.In a right-angled triangle, one of the other two angles is 70°. What is the third angle (in degrees)?
  22. 22.The angles of a triangle are in the ratio 1 : 2 : 2. What is the biggest angle (in degrees)?
  23. 23.In an isosceles triangle, the angle between the two equal sides is 28°. What is each of the other two angles (in degrees)?
  24. 24.An exterior angle of a triangle is 107°. One of its two interior opposite angles is 42°. What is the other one (in degrees)?
  25. 25.In triangle ABC, angle A = 37° and angle B = 78°. What is angle C (in degrees)?
  26. 26.The two interior opposite angles of a triangle are 34° and 49°. What is the exterior angle (in degrees)?
  27. 27.Can a triangle have sides of 10 cm, 20 cm and 8 cm? (a) Yes (b) No
  28. 28.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)?
  29. 29.An exterior angle of a triangle is 89°. One of its two interior opposite angles is 54°. What is the other one (in degrees)?
  30. 30.The two interior opposite angles of a triangle are 37° and 52°. What is the exterior angle (in degrees)?
  31. 31.The two shorter sides of a right-angled triangle are 6 cm and 8 cm. How long is the longest side (in cm)?
  32. 32.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  33. 33.In an isosceles triangle, the two equal angles are 78° each. What is the third angle (in degrees)?
  34. 34.In triangle ABC, angle A = 75° and angle B = 66°. What is angle C (in degrees)?
  35. 35.In a right-angled triangle, one of the other two angles is 72°. What is the third angle (in degrees)?
  36. 36.An exterior angle of a triangle is 88°. One of its two interior opposite angles is 30°. What is the other one (in degrees)?
  37. 37.In a right-angled triangle, one of the other two angles is 71°. What is the third angle (in degrees)?
  38. 38.An exterior angle of a triangle is 88°. One of its two interior opposite angles is 20°. What is the other one (in degrees)?
  39. 39.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  40. 40.The angles of a triangle are in the ratio 1 : 2 : 3. What is the smallest angle (in degrees)?

Answer key

  1. No
  2. 25
  3. 17
  4. 46
  5. 75
  6. 86
  7. 47
  8. 39
  9. 72
  10. 58
  11. 12
  12. 34
  13. 34
  14. 132
  15. 14
  16. No
  17. 149
  18. 70
  19. 25
  20. 120
  21. 20
  22. 72
  23. 76
  24. 65
  25. 65
  26. 83
  27. No
  28. 15
  29. 35
  30. 89
  31. 10
  32. 40
  33. 24
  34. 39
  35. 18
  36. 58
  37. 19
  38. 68
  39. 80
  40. 30

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