← 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 993 · 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 30° and 45°. What is the exterior angle (in degrees)?
  2. 2.The two interior opposite angles of a triangle are 40° and 20°. What is the exterior angle (in degrees)?
  3. 3.An exterior angle of a triangle is 93°. One of its two interior opposite angles is 64°. What is the other one (in degrees)?
  4. 4.The two interior opposite angles of a triangle are 48° and 27°. What is the exterior angle (in degrees)?
  5. 5.In a right-angled triangle, one of the other two angles is 60°. What is the third angle (in degrees)?
  6. 6.In a right-angled triangle, one of the other two angles is 67°. What is the third angle (in degrees)?
  7. 7.Can a triangle have sides of 11 cm, 3 cm and 4 cm? (a) No (b) Yes
  8. 8.An exterior angle of a triangle is 69°. One of its two interior opposite angles is 26°. What is the other one (in degrees)?
  9. 9.In triangle ABC, angle A = 27° and angle B = 111°. What is angle C (in degrees)?
  10. 10.In triangle ABC, angle A = 78° and angle B = 31°. What is angle C (in degrees)?
  11. 11.In a right-angled triangle, one of the other two angles is 41°. What is the third angle (in degrees)?
  12. 12.In triangle ABC, angle A = 75° and angle B = 67°. What is angle C (in degrees)?
  13. 13.The two interior opposite angles of a triangle are 66° and 31°. What is the exterior angle (in degrees)?
  14. 14.The angles of a triangle are in the ratio 2 : 7 : 9. What is the biggest angle (in degrees)?
  15. 15.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (in degrees)?
  16. 16.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  17. 17.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?
  18. 18.An exterior angle of a triangle is 102°. One of its two interior opposite angles is 26°. What is the other one (in degrees)?
  19. 19.In triangle ABC, angle A = 46° and angle B = 53°. What is angle C (in degrees)?
  20. 20.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  21. 21.In a right-angled triangle, one of the other two angles is 64°. What is the third angle (in degrees)?
  22. 22.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  23. 23.Can a triangle have sides of 12 cm, 4 cm and 5 cm? (a) No (b) Yes
  24. 24.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  25. 25.In an isosceles triangle, the two equal angles are 45° each. What is the third angle (in degrees)?
  26. 26.The two interior opposite angles of a triangle are 34° and 56°. What is the exterior angle (in degrees)?
  27. 27.Can a triangle have sides of 10 cm, 10 cm and 12 cm? (a) No (b) Yes
  28. 28.Can a triangle have sides of 8 cm, 14 cm and 8 cm? (a) Yes (b) No
  29. 29.Can a triangle have sides of 12 cm, 5 cm and 19 cm? (a) No (b) Yes
  30. 30.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  31. 31.In triangle ABC, angle A = 48° and angle B = 81°. What is angle C (in degrees)?
  32. 32.Can a triangle have sides of 3 cm, 2 cm and 4 cm? (a) Yes (b) No
  33. 33.The angles of a triangle are in the ratio 2 : 2 : 5. What is the smallest angle (in degrees)?
  34. 34.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  35. 35.In an isosceles triangle, the angle between the two equal sides is 84°. What is each of the other two angles (in degrees)?
  36. 36.Can a triangle have sides of 5 cm, 6 cm and 5 cm? (a) Yes (b) No
  37. 37.The two shorter sides of a right-angled triangle are 24 cm and 10 cm. How long is the longest side (in cm)?
  38. 38.The two shorter sides of a right-angled triangle are 3 cm and 4 cm. How long is the longest side (in cm)?
  39. 39.Can a triangle have sides of 2 cm, 6 cm and 4 cm? (a) Yes (b) No
  40. 40.In triangle ABC, angle A = 71° and angle B = 71°. What is angle C (in degrees)?

Answer key

  1. 75
  2. 60
  3. 29
  4. 75
  5. 30
  6. 23
  7. No
  8. 43
  9. 42
  10. 71
  11. 49
  12. 38
  13. 97
  14. 90
  15. 72
  16. 100
  17. 50
  18. 76
  19. 81
  20. 18
  21. 26
  22. 90
  23. No
  24. 75
  25. 90
  26. 90
  27. Yes
  28. Yes
  29. No
  30. 45
  31. 51
  32. Yes
  33. 40
  34. 90
  35. 48
  36. Yes
  37. 26
  38. 5
  39. No
  40. 38

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