← 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 399 · 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, 7 cm and 8 cm? (a) Yes (b) No
  2. 2.The longest side of a right-angled triangle is 30 cm and one of the other sides is 24 cm. How long is the third side (in cm)?
  3. 3.The two shorter sides of a right-angled triangle are 10 cm and 24 cm. How long is the longest side (in cm)?
  4. 4.In triangle ABC, angle A = 40° and angle B = 107°. What is angle C (in degrees)?
  5. 5.In a right-angled triangle, one of the other two angles is 17°. What is the third angle (in degrees)?
  6. 6.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  7. 7.The two interior opposite angles of a triangle are 22° and 28°. What is the exterior angle (in degrees)?
  8. 8.Can a triangle have sides of 9 cm, 5 cm and 7 cm? (a) Yes (b) No
  9. 9.In triangle ABC, angle A = 34° and angle B = 102°. What is angle C (in degrees)?
  10. 10.Can a triangle have sides of 12 cm, 3 cm and 5 cm? (a) Yes (b) No
  11. 11.The angles of a triangle are in the ratio 3 : 3 : 4. What is the smallest angle (in degrees)?
  12. 12.An exterior angle of a triangle is 100°. One of its two interior opposite angles is 45°. What is the other one (in degrees)?
  13. 13.In triangle ABC, angle A = 26° and angle B = 119°. What is angle C (in degrees)?
  14. 14.In triangle ABC, angle A = 23° and angle B = 102°. What is angle C (in degrees)?
  15. 15.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  16. 16.In an isosceles triangle, the two equal angles are 55° each. What is the third angle (in degrees)?
  17. 17.In an isosceles triangle, the angle between the two equal sides is 90°. What is each of the other two angles (in degrees)?
  18. 18.In a right-angled triangle, one of the other two angles is 55°. What is the third angle (in degrees)?
  19. 19.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  20. 20.In triangle ABC, angle A = 91° and angle B = 59°. What is angle C (in degrees)?
  21. 21.Can a triangle have sides of 12 cm, 3 cm and 16 cm? (a) Yes (b) No
  22. 22.In an isosceles triangle, the two equal angles are 52° each. What is the third angle (in degrees)?
  23. 23.An exterior angle of a triangle is 91°. One of its two interior opposite angles is 23°. What is the other one (in degrees)?
  24. 24.In a right-angled triangle, one of the other two angles is 60°. What is the third angle (in degrees)?
  25. 25.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)?
  26. 26.An exterior angle of a triangle is 75°. One of its two interior opposite angles is 45°. What is the other one (in degrees)?
  27. 27.The two interior opposite angles of a triangle are 21° and 52°. What is the exterior angle (in degrees)?
  28. 28.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)?
  29. 29.In an isosceles triangle, the angle between the two equal sides is 78°. What is each of the other two angles (in degrees)?
  30. 30.The angles of a triangle are in the ratio 1 : 1 : 2. What is the smallest angle (in degrees)?
  31. 31.In an isosceles triangle, the angle between the two equal sides is 42°. What is each of the other two angles (in degrees)?
  32. 32.The two interior opposite angles of a triangle are 41° and 69°. What is the exterior angle (in degrees)?
  33. 33.In an isosceles triangle, the angle between the two equal sides is 120°. What is each of the other two angles (in degrees)?
  34. 34.In an isosceles triangle, the two equal angles are 45° each. What is the third angle (in degrees)?
  35. 35.The two interior opposite angles of a triangle are 28° and 59°. What is the exterior angle (in degrees)?
  36. 36.In an isosceles triangle, the angle between the two equal sides is 124°. What is each of the other two angles (in degrees)?
  37. 37.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  38. 38.The two interior opposite angles of a triangle are 32° and 20°. What is the exterior angle (in degrees)?
  39. 39.Can a triangle have sides of 6 cm, 13 cm and 6 cm? (a) Yes (b) No
  40. 40.Can a triangle have sides of 2 cm, 3 cm and 6 cm? (a) No (b) Yes

Answer key

  1. No
  2. 18
  3. 26
  4. 33
  5. 73
  6. 17
  7. 50
  8. Yes
  9. 44
  10. No
  11. 54
  12. 55
  13. 35
  14. 55
  15. 90
  16. 70
  17. 45
  18. 35
  19. 45
  20. 30
  21. No
  22. 76
  23. 68
  24. 30
  25. 15
  26. 30
  27. 73
  28. 8
  29. 51
  30. 45
  31. 69
  32. 110
  33. 30
  34. 90
  35. 87
  36. 28
  37. 90
  38. 52
  39. No
  40. No

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