← 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 189 · 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 81°. One of its two interior opposite angles is 47°. What is the other one (in degrees)?
  2. 2.In a right-angled triangle, one of the other two angles is 32°. What is the third angle (in degrees)?
  3. 3.The angles of a triangle are in the ratio 1 : 2 : 3. What is the biggest angle (in degrees)?
  4. 4.In triangle ABC, angle A = 71° and angle B = 49°. What is angle C (in degrees)?
  5. 5.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  6. 6.In an isosceles triangle, the angle between the two equal sides is 118°. What is each of the other two angles (in degrees)?
  7. 7.In triangle ABC, angle A = 28° and angle B = 34°. What is angle C (in degrees)?
  8. 8.In a right-angled triangle, one of the other two angles is 52°. What is the third angle (in degrees)?
  9. 9.In a right-angled triangle, one of the other two angles is 56°. What is the third angle (in degrees)?
  10. 10.The two shorter sides of a right-angled triangle are 12 cm and 16 cm. How long is the longest side (in cm)?
  11. 11.Can a triangle have sides of 11 cm, 7 cm and 2 cm? (a) No (b) Yes
  12. 12.In an isosceles triangle, the angle between the two equal sides is 50°. What is each of the other two angles (in degrees)?
  13. 13.Can a triangle have sides of 11 cm, 9 cm and 3 cm? (a) No (b) Yes
  14. 14.Can a triangle have sides of 11 cm, 4 cm and 10 cm? (a) Yes (b) No
  15. 15.The angles of a triangle are in the ratio 5 : 6 : 7. What is the biggest angle (in degrees)?
  16. 16.In an isosceles triangle, the two equal angles are 27° each. What is the third angle (in degrees)?
  17. 17.Can a triangle have sides of 10 cm, 16 cm and 6 cm? (a) No (b) Yes
  18. 18.In an isosceles triangle, the two equal angles are 45° each. What is the third angle (in degrees)?
  19. 19.In triangle ABC, angle A = 58° and angle B = 63°. What is angle C (in degrees)?
  20. 20.In triangle ABC, angle A = 64° and angle B = 78°. What is angle C (in degrees)?
  21. 21.In a right-angled triangle, one of the other two angles is 55°. What is the third angle (in degrees)?
  22. 22.An exterior angle of a triangle is 142°. One of its two interior opposite angles is 78°. What is the other one (in degrees)?
  23. 23.The two shorter sides of a right-angled triangle are 20 cm and 15 cm. How long is the longest side (in cm)?
  24. 24.Can a triangle have sides of 10 cm, 2 cm and 7 cm? (a) Yes (b) No
  25. 25.In a right-angled triangle, one of the other two angles is 54°. What is the third angle (in degrees)?
  26. 26.In an isosceles triangle, the two equal angles are 22° each. What is the third angle (in degrees)?
  27. 27.The two interior opposite angles of a triangle are 26° and 21°. What is the exterior angle (in degrees)?
  28. 28.The angles of a triangle are in the ratio 1 : 2 : 2. What is the biggest angle (in degrees)?
  29. 29.Can a triangle have sides of 8 cm, 5 cm and 15 cm? (a) No (b) Yes
  30. 30.In an isosceles triangle, the angle between the two equal sides is 28°. What is each of the other two angles (in degrees)?
  31. 31.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  32. 32.Can a triangle have sides of 13 cm, 3 cm and 6 cm? (a) Yes (b) No
  33. 33.In an isosceles triangle, the two equal angles are 21° each. What is the third angle (in degrees)?
  34. 34.The two interior opposite angles of a triangle are 23° and 35°. What is the exterior angle (in degrees)?
  35. 35.In an isosceles triangle, the two equal angles are 42° each. What is the third angle (in degrees)?
  36. 36.In triangle ABC, angle A = 48° and angle B = 63°. What is angle C (in degrees)?
  37. 37.In a right-angled triangle, one of the other two angles is 33°. What is the third angle (in degrees)?
  38. 38.In a right-angled triangle, one of the other two angles is 51°. What is the third angle (in degrees)?
  39. 39.Can a triangle have sides of 9 cm, 2 cm and 2 cm? (a) Yes (b) No
  40. 40.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?

Answer key

  1. 34
  2. 58
  3. 90
  4. 60
  5. 25
  6. 31
  7. 118
  8. 38
  9. 34
  10. 20
  11. No
  12. 65
  13. Yes
  14. Yes
  15. 70
  16. 126
  17. No
  18. 90
  19. 59
  20. 38
  21. 35
  22. 64
  23. 25
  24. No
  25. 36
  26. 136
  27. 47
  28. 72
  29. No
  30. 76
  31. 20
  32. No
  33. 138
  34. 58
  35. 96
  36. 69
  37. 57
  38. 39
  39. No
  40. 36

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