← 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 973 · 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.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)?
  2. 2.Can a triangle have sides of 15 cm, 9 cm and 10 cm? (a) Yes (b) No
  3. 3.The angles of a triangle are in the ratio 5 : 6 : 7. What is the biggest angle (in degrees)?
  4. 4.In triangle ABC, angle A = 37° and angle B = 109°. What is angle C (in degrees)?
  5. 5.In an isosceles triangle, the two equal angles are 31° each. What is the third angle (in degrees)?
  6. 6.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (in degrees)?
  7. 7.In a right-angled triangle, one of the other two angles is 18°. What is the third angle (in degrees)?
  8. 8.The angles of a triangle are in the ratio 2 : 3 : 5. What is the smallest angle (in degrees)?
  9. 9.In a right-angled triangle, one of the other two angles is 47°. What is the third angle (in degrees)?
  10. 10.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)?
  11. 11.Can a triangle have sides of 13 cm, 7 cm and 12 cm? (a) Yes (b) No
  12. 12.In triangle ABC, angle A = 28° and angle B = 22°. What is angle C (in degrees)?
  13. 13.An exterior angle of a triangle is 90°. One of its two interior opposite angles is 50°. What is the other one (in degrees)?
  14. 14.The longest side of a right-angled triangle is 20 cm and one of the other sides is 12 cm. How long is the third side (in cm)?
  15. 15.An exterior angle of a triangle is 57°. One of its two interior opposite angles is 22°. What is the other one (in degrees)?
  16. 16.The two interior opposite angles of a triangle are 55° and 73°. What is the exterior angle (in degrees)?
  17. 17.Can a triangle have sides of 6 cm, 2 cm and 8 cm? (a) No (b) Yes
  18. 18.In triangle ABC, angle A = 27° and angle B = 120°. What is angle C (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.The two interior opposite angles of a triangle are 60° and 68°. What is the exterior angle (in degrees)?
  21. 21.In an isosceles triangle, the angle between the two equal sides is 44°. What is each of the other two angles (in degrees)?
  22. 22.In triangle ABC, angle A = 57° and angle B = 85°. What is angle C (in degrees)?
  23. 23.In triangle ABC, angle A = 91° and angle B = 26°. What is angle C (in degrees)?
  24. 24.In triangle ABC, angle A = 78° and angle B = 60°. What is angle C (in degrees)?
  25. 25.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  26. 26.An exterior angle of a triangle is 113°. One of its two interior opposite angles is 73°. What is the other one (in degrees)?
  27. 27.Can a triangle have sides of 9 cm, 2 cm and 2 cm? (a) Yes (b) No
  28. 28.In an isosceles triangle, the angle between the two equal sides is 34°. What is each of the other two angles (in degrees)?
  29. 29.In an isosceles triangle, the angle between the two equal sides is 42°. What is each of the other two angles (in degrees)?
  30. 30.The two interior opposite angles of a triangle are 26° and 72°. What is the exterior angle (in degrees)?
  31. 31.In triangle ABC, angle A = 57° and angle B = 84°. What is angle C (in degrees)?
  32. 32.In a right-angled triangle, one of the other two angles is 46°. 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 8 cm. How long is the third side (in cm)?
  34. 34.Can a triangle have sides of 12 cm, 9 cm and 7 cm? (a) Yes (b) No
  35. 35.In triangle ABC, angle A = 57° and angle B = 83°. What is angle C (in degrees)?
  36. 36.In an isosceles triangle, the angle between the two equal sides is 20°. What is each of the other two angles (in degrees)?
  37. 37.Can a triangle have sides of 4 cm, 9 cm and 5 cm? (a) No (b) Yes
  38. 38.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  39. 39.The two shorter sides of a right-angled triangle are 4 cm and 3 cm. How long is the longest side (in cm)?
  40. 40.In an isosceles triangle, the angle between the two equal sides is 160°. What is each of the other two angles (in degrees)?

Answer key

  1. 12
  2. Yes
  3. 70
  4. 34
  5. 118
  6. 72
  7. 72
  8. 36
  9. 43
  10. 6
  11. Yes
  12. 130
  13. 40
  14. 16
  15. 35
  16. 128
  17. No
  18. 33
  19. 10
  20. 128
  21. 68
  22. 38
  23. 63
  24. 42
  25. 100
  26. 40
  27. No
  28. 73
  29. 69
  30. 98
  31. 39
  32. 44
  33. 15
  34. Yes
  35. 40
  36. 80
  37. No
  38. 17
  39. 5
  40. 10

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