← 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 986 · 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 an isosceles triangle, the two equal angles are 53° each. What is the third angle (in degrees)?
  2. 2.In a right-angled triangle, one of the other two angles is 27°. What is the third angle (in degrees)?
  3. 3.Can a triangle have sides of 11 cm, 4 cm and 10 cm? (a) Yes (b) No
  4. 4.Can a triangle have sides of 3 cm, 7 cm and 7 cm? (a) No (b) Yes
  5. 5.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  6. 6.The two interior opposite angles of a triangle are 27° and 54°. What is the exterior angle (in degrees)?
  7. 7.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  8. 8.In triangle ABC, angle A = 80° and angle B = 26°. What is angle C (in degrees)?
  9. 9.The angles of a triangle are in the ratio 2 : 2 : 5. What is the smallest angle (in degrees)?
  10. 10.Can a triangle have sides of 8 cm, 3 cm and 12 cm? (a) No (b) Yes
  11. 11.In triangle ABC, angle A = 84° and angle B = 23°. What is angle C (in degrees)?
  12. 12.The longest side of a right-angled triangle is 13 cm and one of the other sides is 12 cm. How long is the third side (in cm)?
  13. 13.Can a triangle have sides of 12 cm, 8 cm and 9 cm? (a) No (b) Yes
  14. 14.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  15. 15.An exterior angle of a triangle is 125°. One of its two interior opposite angles is 63°. What is the other one (in degrees)?
  16. 16.In an isosceles triangle, the two equal angles are 47° each. What is the third angle (in degrees)?
  17. 17.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  18. 18.In triangle ABC, angle A = 95° and angle B = 47°. What is angle C (in degrees)?
  19. 19.The longest side of a right-angled triangle is 25 cm and one of the other sides is 7 cm. How long is the third side (in cm)?
  20. 20.In an isosceles triangle, the two equal angles are 50° each. What is the third angle (in degrees)?
  21. 21.In triangle ABC, angle A = 70° and angle B = 51°. What is angle C (in degrees)?
  22. 22.An exterior angle of a triangle is 130°. One of its two interior opposite angles is 64°. What is the other one (in degrees)?
  23. 23.In an isosceles triangle, the angle between the two equal sides is 104°. What is each of the other two angles (in degrees)?
  24. 24.In triangle ABC, angle A = 66° and angle B = 60°. What is angle C (in degrees)?
  25. 25.In a right-angled triangle, one of the other two angles is 18°. What is the third angle (in degrees)?
  26. 26.In an isosceles triangle, the two equal angles are 26° each. What is the third angle (in degrees)?
  27. 27.In a right-angled triangle, one of the other two angles is 76°. What is the third angle (in degrees)?
  28. 28.Can a triangle have sides of 9 cm, 16 cm and 6 cm? (a) No (b) Yes
  29. 29.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)?
  30. 30.In triangle ABC, angle A = 29° and angle B = 38°. What is angle C (in degrees)?
  31. 31.In a right-angled triangle, one of the other two angles is 28°. What is the third angle (in degrees)?
  32. 32.In triangle ABC, angle A = 71° and angle B = 64°. What is angle C (in degrees)?
  33. 33.In a right-angled triangle, one of the other two angles is 63°. What is the third angle (in degrees)?
  34. 34.The two interior opposite angles of a triangle are 25° and 64°. What is the exterior angle (in degrees)?
  35. 35.In triangle ABC, angle A = 57° and angle B = 80°. What is angle C (in degrees)?
  36. 36.In a right-angled triangle, one of the other two angles is 44°. What is the third angle (in degrees)?
  37. 37.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?
  38. 38.In triangle ABC, angle A = 60° and angle B = 98°. What is angle C (in degrees)?
  39. 39.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 56°. What is the third angle (in degrees)?

Answer key

  1. 74
  2. 63
  3. Yes
  4. Yes
  5. 36
  6. 81
  7. 100
  8. 74
  9. 40
  10. No
  11. 73
  12. 5
  13. Yes
  14. 18
  15. 62
  16. 86
  17. 25
  18. 38
  19. 24
  20. 80
  21. 59
  22. 66
  23. 38
  24. 54
  25. 72
  26. 128
  27. 14
  28. No
  29. 8
  30. 113
  31. 62
  32. 45
  33. 27
  34. 89
  35. 43
  36. 46
  37. 48
  38. 22
  39. 50
  40. 34

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