← 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 952 · 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 18 cm, 10 cm and 5 cm? (a) No (b) Yes
  2. 2.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  3. 3.The two shorter sides of a right-angled triangle are 15 cm and 20 cm. How long is the longest side (in cm)?
  4. 4.In triangle ABC, angle A = 63° and angle B = 54°. What is angle C (in degrees)?
  5. 5.An exterior angle of a triangle is 146°. One of its two interior opposite angles is 74°. What is the other one (in degrees)?
  6. 6.In an isosceles triangle, the angle between the two equal sides is 108°. What is each of the other two angles (in degrees)?
  7. 7.The longest side of a right-angled triangle is 10 cm and one of the other sides is 8 cm. How long is the third side (in cm)?
  8. 8.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  9. 9.An exterior angle of a triangle is 57°. One of its two interior opposite angles is 34°. What is the other one (in degrees)?
  10. 10.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  11. 11.An exterior angle of a triangle is 88°. One of its two interior opposite angles is 22°. What is the other one (in degrees)?
  12. 12.In a right-angled triangle, one of the other two angles is 55°. What is the third angle (in degrees)?
  13. 13.In an isosceles triangle, the angle between the two equal sides is 152°. What is each of the other two angles (in degrees)?
  14. 14.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?
  15. 15.The two interior opposite angles of a triangle are 24° and 58°. What is the exterior angle (in degrees)?
  16. 16.In a right-angled triangle, one of the other two angles is 75°. What is the third angle (in degrees)?
  17. 17.In triangle ABC, angle A = 77° and angle B = 55°. What is angle C (in degrees)?
  18. 18.Can a triangle have sides of 1 cm, 10 cm and 10 cm? (a) No (b) Yes
  19. 19.Can a triangle have sides of 14 cm, 3 cm and 9 cm? (a) Yes (b) No
  20. 20.Can a triangle have sides of 9 cm, 10 cm and 23 cm? (a) No (b) Yes
  21. 21.In an isosceles triangle, the angle between the two equal sides is 90°. What is each of the other two angles (in degrees)?
  22. 22.Can a triangle have sides of 2 cm, 9 cm and 6 cm? (a) Yes (b) No
  23. 23.In a right-angled triangle, one of the other two angles is 14°. What is the third angle (in degrees)?
  24. 24.The two shorter sides of a right-angled triangle are 12 cm and 5 cm. How long is the longest side (in cm)?
  25. 25.In an isosceles triangle, the two equal angles are 24° each. What is the third angle (in degrees)?
  26. 26.The two shorter sides of a right-angled triangle are 24 cm and 10 cm. How long is the longest side (in cm)?
  27. 27.In triangle ABC, angle A = 89° and angle B = 30°. What is angle C (in degrees)?
  28. 28.The two interior opposite angles of a triangle are 57° and 38°. What is the exterior angle (in degrees)?
  29. 29.Can a triangle have sides of 6 cm, 7 cm and 17 cm? (a) No (b) Yes
  30. 30.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)?
  31. 31.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  32. 32.In triangle ABC, angle A = 56° and angle B = 61°. What is angle C (in degrees)?
  33. 33.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  34. 34.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  35. 35.Can a triangle have sides of 6 cm, 6 cm and 7 cm? (a) No (b) Yes
  36. 36.In a right-angled triangle, one of the other two angles is 20°. What is the third angle (in degrees)?
  37. 37.In triangle ABC, angle A = 73° and angle B = 72°. What is angle C (in degrees)?
  38. 38.An exterior angle of a triangle is 119°. One of its two interior opposite angles is 55°. What is the other one (in degrees)?
  39. 39.In an isosceles triangle, the two equal angles are 21° each. What is the third angle (in degrees)?
  40. 40.In an isosceles triangle, the angle between the two equal sides is 118°. What is each of the other two angles (in degrees)?

Answer key

  1. No
  2. 90
  3. 25
  4. 63
  5. 72
  6. 36
  7. 6
  8. 18
  9. 23
  10. 72
  11. 66
  12. 35
  13. 14
  14. 48
  15. 82
  16. 15
  17. 48
  18. Yes
  19. No
  20. No
  21. 45
  22. No
  23. 76
  24. 13
  25. 132
  26. 26
  27. 61
  28. 95
  29. No
  30. 10
  31. 36
  32. 63
  33. 20
  34. 90
  35. Yes
  36. 70
  37. 35
  38. 64
  39. 138
  40. 31

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