← 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 270 · 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 two interior opposite angles of a triangle are 26° and 41°. What is the exterior angle (in degrees)?
  2. 2.The two interior opposite angles of a triangle are 80° and 32°. What is the exterior angle (in degrees)?
  3. 3.In a right-angled triangle, one of the other two angles is 20°. What is the third angle (in degrees)?
  4. 4.The angles of a triangle are in the ratio 2 : 2 : 5. What is the smallest angle (in degrees)?
  5. 5.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  6. 6.The longest side of a right-angled triangle is 39 cm and one of the other sides is 36 cm. How long is the third side (in cm)?
  7. 7.Can a triangle have sides of 9 cm, 9 cm and 7 cm? (a) No (b) Yes
  8. 8.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  9. 9.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  10. 10.The two interior opposite angles of a triangle are 50° and 37°. What is the exterior angle (in degrees)?
  11. 11.An exterior angle of a triangle is 87°. One of its two interior opposite angles is 62°. What is the other one (in degrees)?
  12. 12.An exterior angle of a triangle is 63°. One of its two interior opposite angles is 36°. What is the other one (in degrees)?
  13. 13.The angles of a triangle are in the ratio 3 : 3 : 4. What is the smallest angle (in degrees)?
  14. 14.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  15. 15.The two interior opposite angles of a triangle are 72° and 54°. What is the exterior angle (in degrees)?
  16. 16.Can a triangle have sides of 19 cm, 7 cm and 11 cm? (a) No (b) Yes
  17. 17.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  18. 18.Can a triangle have sides of 5 cm, 11 cm and 9 cm? (a) No (b) Yes
  19. 19.The two interior opposite angles of a triangle are 70° and 49°. What is the exterior angle (in degrees)?
  20. 20.In triangle ABC, angle A = 88° and angle B = 21°. What is angle C (in degrees)?
  21. 21.In a right-angled triangle, one of the other two angles is 17°. What is the third angle (in degrees)?
  22. 22.In an isosceles triangle, the angle between the two equal sides is 76°. What is each of the other two angles (in degrees)?
  23. 23.An exterior angle of a triangle is 102°. One of its two interior opposite angles is 37°. What is the other one (in degrees)?
  24. 24.Can a triangle have sides of 7 cm, 21 cm and 12 cm? (a) Yes (b) No
  25. 25.In an isosceles triangle, the angle between the two equal sides is 150°. What is each of the other two angles (in degrees)?
  26. 26.The angles of a triangle are in the ratio 3 : 5 : 7. What is the biggest angle (in degrees)?
  27. 27.In triangle ABC, angle A = 34° and angle B = 91°. What is angle C (in degrees)?
  28. 28.An exterior angle of a triangle is 78°. One of its two interior opposite angles is 22°. What is the other one (in degrees)?
  29. 29.Can a triangle have sides of 12 cm, 6 cm and 4 cm? (a) No (b) Yes
  30. 30.In an isosceles triangle, the two equal angles are 20° each. What is the third angle (in degrees)?
  31. 31.In a right-angled triangle, one of the other two angles is 60°. What is the third angle (in degrees)?
  32. 32.In an isosceles triangle, the angle between the two equal sides is 116°. What is each of the other two angles (in degrees)?
  33. 33.In triangle ABC, angle A = 76° and angle B = 67°. What is angle C (in degrees)?
  34. 34.The angles of a triangle are in the ratio 2 : 7 : 9. What is the biggest angle (in degrees)?
  35. 35.The two shorter sides of a right-angled triangle are 15 cm and 20 cm. How long is the longest side (in cm)?
  36. 36.In triangle ABC, angle A = 46° and angle B = 47°. What is angle C (in degrees)?
  37. 37.The longest side of a right-angled triangle is 39 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  38. 38.In triangle ABC, angle A = 97° and angle B = 45°. What is angle C (in degrees)?
  39. 39.In triangle ABC, angle A = 68° and angle B = 53°. What is angle C (in degrees)?
  40. 40.The two shorter sides of a right-angled triangle are 8 cm and 6 cm. How long is the longest side (in cm)?

Answer key

  1. 67
  2. 112
  3. 70
  4. 40
  5. 40
  6. 15
  7. Yes
  8. 20
  9. 25
  10. 87
  11. 25
  12. 27
  13. 54
  14. 80
  15. 126
  16. No
  17. 90
  18. Yes
  19. 119
  20. 71
  21. 73
  22. 52
  23. 65
  24. No
  25. 15
  26. 84
  27. 55
  28. 56
  29. No
  30. 140
  31. 30
  32. 32
  33. 37
  34. 90
  35. 25
  36. 87
  37. 36
  38. 38
  39. 59
  40. 10

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