← 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 555 · 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.An exterior angle of a triangle is 104°. One of its two interior opposite angles is 66°. What is the other one (in degrees)?
  2. 2.In an isosceles triangle, the two equal angles are 46° each. What is the third angle (in degrees)?
  3. 3.Can a triangle have sides of 12 cm, 6 cm and 20 cm? (a) Yes (b) No
  4. 4.An exterior angle of a triangle is 110°. One of its two interior opposite angles is 34°. What is the other one (in degrees)?
  5. 5.Can a triangle have sides of 10 cm, 10 cm and 2 cm? (a) No (b) Yes
  6. 6.Can a triangle have sides of 6 cm, 11 cm and 14 cm? (a) No (b) Yes
  7. 7.Can a triangle have sides of 8 cm, 7 cm and 2 cm? (a) Yes (b) No
  8. 8.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)?
  9. 9.In a right-angled triangle, one of the other two angles is 39°. What is the third angle (in degrees)?
  10. 10.The angles of a triangle are in the ratio 1 : 2 : 6. What is the smallest angle (in degrees)?
  11. 11.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  12. 12.The two interior opposite angles of a triangle are 72° and 47°. What is the exterior angle (in degrees)?
  13. 13.An exterior angle of a triangle is 71°. One of its two interior opposite angles is 20°. What is the other one (in degrees)?
  14. 14.Can a triangle have sides of 2 cm, 2 cm and 2 cm? (a) No (b) Yes
  15. 15.The two shorter sides of a right-angled triangle are 18 cm and 24 cm. How long is the longest side (in cm)?
  16. 16.In a right-angled triangle, one of the other two angles is 15°. What is the third angle (in degrees)?
  17. 17.An exterior angle of a triangle is 63°. One of its two interior opposite angles is 41°. What is the other one (in degrees)?
  18. 18.In triangle ABC, angle A = 88° and angle B = 21°. What is angle C (in degrees)?
  19. 19.In triangle ABC, angle A = 95° and angle B = 20°. What is angle C (in degrees)?
  20. 20.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?
  21. 21.The angles of a triangle are in the ratio 3 : 5 : 7. What is the biggest angle (in degrees)?
  22. 22.In triangle ABC, angle A = 100° and angle B = 22°. What is angle C (in degrees)?
  23. 23.The two interior opposite angles of a triangle are 20° and 25°. What is the exterior angle (in degrees)?
  24. 24.The angles of a triangle are in the ratio 2 : 7 : 9. What is the biggest angle (in degrees)?
  25. 25.In a right-angled triangle, one of the other two angles is 56°. What is the third angle (in degrees)?
  26. 26.In triangle ABC, angle A = 26° and angle B = 129°. What is angle C (in degrees)?
  27. 27.In a right-angled triangle, one of the other two angles is 41°. What is the third angle (in degrees)?
  28. 28.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  29. 29.The two interior opposite angles of a triangle are 75° and 44°. What is the exterior angle (in degrees)?
  30. 30.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  31. 31.In triangle ABC, angle A = 30° and angle B = 74°. What is angle C (in degrees)?
  32. 32.An exterior angle of a triangle is 93°. One of its two interior opposite angles is 26°. What is the other one (in degrees)?
  33. 33.In an isosceles triangle, the two equal angles are 51° each. What is the third angle (in degrees)?
  34. 34.Can a triangle have sides of 10 cm, 10 cm and 4 cm? (a) No (b) Yes
  35. 35.The angles of a triangle are in the ratio 1 : 2 : 3. What is the biggest angle (in degrees)?
  36. 36.In a right-angled triangle, one of the other two angles is 42°. What is the third angle (in degrees)?
  37. 37.In an isosceles triangle, the angle between the two equal sides is 20°. What is each of the other two angles (in degrees)?
  38. 38.In a right-angled triangle, one of the other two angles is 63°. What is the third angle (in degrees)?
  39. 39.In triangle ABC, angle A = 57° and angle B = 97°. What is angle C (in degrees)?
  40. 40.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?

Answer key

  1. 38
  2. 88
  3. No
  4. 76
  5. Yes
  6. Yes
  7. Yes
  8. 15
  9. 51
  10. 20
  11. 18
  12. 119
  13. 51
  14. Yes
  15. 30
  16. 75
  17. 22
  18. 71
  19. 65
  20. 50
  21. 84
  22. 58
  23. 45
  24. 90
  25. 34
  26. 25
  27. 49
  28. 90
  29. 119
  30. 25
  31. 76
  32. 67
  33. 78
  34. Yes
  35. 90
  36. 48
  37. 80
  38. 27
  39. 26
  40. 45

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