← 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 890 · 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.In triangle ABC, angle A = 24° and angle B = 122°. What is angle C (in degrees)?
  2. 2.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  3. 3.The two interior opposite angles of a triangle are 75° and 71°. What is the exterior angle (in degrees)?
  4. 4.An exterior angle of a triangle is 98°. One of its two interior opposite angles is 37°. What is the other one (in degrees)?
  5. 5.In a right-angled triangle, one of the other two angles is 26°. What is the third angle (in degrees)?
  6. 6.Can a triangle have sides of 6 cm, 11 cm and 4 cm? (a) No (b) Yes
  7. 7.In a right-angled triangle, one of the other two angles is 79°. What is the third angle (in degrees)?
  8. 8.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  9. 9.In an isosceles triangle, the angle between the two equal sides is 136°. What is each of the other two angles (in degrees)?
  10. 10.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)?
  11. 11.In an isosceles triangle, the angle between the two equal sides is 104°. What is each of the other two angles (in degrees)?
  12. 12.Can a triangle have sides of 10 cm, 4 cm and 12 cm? (a) No (b) Yes
  13. 13.Can a triangle have sides of 3 cm, 11 cm and 10 cm? (a) No (b) Yes
  14. 14.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  15. 15.The angles of a triangle are in the ratio 1 : 1 : 2. What is the smallest angle (in degrees)?
  16. 16.Can a triangle have sides of 9 cm, 10 cm and 4 cm? (a) No (b) Yes
  17. 17.In a right-angled triangle, one of the other two angles is 30°. What is the third angle (in degrees)?
  18. 18.In triangle ABC, angle A = 71° and angle B = 35°. What is angle C (in degrees)?
  19. 19.An exterior angle of a triangle is 74°. One of its two interior opposite angles is 47°. What is the other one (in degrees)?
  20. 20.In a right-angled triangle, one of the other two angles is 14°. What is the third angle (in degrees)?
  21. 21.In triangle ABC, angle A = 68° and angle B = 39°. What is angle C (in degrees)?
  22. 22.In triangle ABC, angle A = 48° and angle B = 107°. What is angle C (in degrees)?
  23. 23.Can a triangle have sides of 12 cm, 9 cm and 2 cm? (a) Yes (b) No
  24. 24.In an isosceles triangle, the angle between the two equal sides is 20°. What is each of the other two angles (in degrees)?
  25. 25.An exterior angle of a triangle is 67°. One of its two interior opposite angles is 39°. What is the other one (in degrees)?
  26. 26.An exterior angle of a triangle is 145°. One of its two interior opposite angles is 77°. What is the other one (in degrees)?
  27. 27.The two interior opposite angles of a triangle are 80° and 78°. What is the exterior angle (in degrees)?
  28. 28.Can a triangle have sides of 12 cm, 3 cm and 8 cm? (a) Yes (b) No
  29. 29.An exterior angle of a triangle is 136°. One of its two interior opposite angles is 59°. What is the other one (in degrees)?
  30. 30.In triangle ABC, angle A = 71° and angle B = 83°. What is angle C (in degrees)?
  31. 31.In an isosceles triangle, the angle between the two equal sides is 76°. What is each of the other two angles (in degrees)?
  32. 32.The angles of a triangle are in the ratio 2 : 2 : 5. What is the smallest angle (in degrees)?
  33. 33.In triangle ABC, angle A = 35° and angle B = 123°. What is angle C (in degrees)?
  34. 34.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  35. 35.The two interior opposite angles of a triangle are 53° and 22°. What is the exterior angle (in degrees)?
  36. 36.In triangle ABC, angle A = 36° and angle B = 83°. What is angle C (in degrees)?
  37. 37.In triangle ABC, angle A = 22° and angle B = 56°. What is angle C (in degrees)?
  38. 38.Can a triangle have sides of 19 cm, 7 cm and 7 cm? (a) No (b) Yes
  39. 39.In triangle ABC, angle A = 32° and angle B = 46°. What is angle C (in degrees)?
  40. 40.The two interior opposite angles of a triangle are 22° and 75°. What is the exterior angle (in degrees)?

Answer key

  1. 34
  2. 17
  3. 146
  4. 61
  5. 64
  6. No
  7. 11
  8. 45
  9. 22
  10. 8
  11. 38
  12. Yes
  13. Yes
  14. 20
  15. 45
  16. Yes
  17. 60
  18. 74
  19. 27
  20. 76
  21. 73
  22. 25
  23. No
  24. 80
  25. 28
  26. 68
  27. 158
  28. No
  29. 77
  30. 26
  31. 52
  32. 40
  33. 22
  34. 100
  35. 75
  36. 61
  37. 102
  38. No
  39. 102
  40. 97

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