← 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 373 · 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.Can a triangle have sides of 6 cm, 18 cm and 9 cm? (a) Yes (b) No
  2. 2.In an isosceles triangle, the two equal angles are 27° each. What is the third angle (in degrees)?
  3. 3.In triangle ABC, angle A = 38° and angle B = 46°. What is angle C (in degrees)?
  4. 4.The two shorter sides of a right-angled triangle are 24 cm and 10 cm. How long is the longest side (in cm)?
  5. 5.The longest side of a right-angled triangle is 5 cm and one of the other sides is 3 cm. How long is the third side (in cm)?
  6. 6.In a right-angled triangle, one of the other two angles is 29°. What is the third angle (in degrees)?
  7. 7.In an isosceles triangle, the two equal angles are 57° each. What is the third angle (in degrees)?
  8. 8.An exterior angle of a triangle is 132°. One of its two interior opposite angles is 69°. What is the other one (in degrees)?
  9. 9.An exterior angle of a triangle is 96°. One of its two interior opposite angles is 51°. What is the other one (in degrees)?
  10. 10.The longest side of a right-angled triangle is 15 cm and one of the other sides is 9 cm. How long is the third side (in cm)?
  11. 11.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  12. 12.The angles of a triangle are in the ratio 1 : 2 : 3. What is the smallest angle (in degrees)?
  13. 13.An exterior angle of a triangle is 73°. One of its two interior opposite angles is 34°. What is the other one (in degrees)?
  14. 14.In triangle ABC, angle A = 99° and angle B = 49°. What is angle C (in degrees)?
  15. 15.In an isosceles triangle, the angle between the two equal sides is 98°. What is each of the other two angles (in degrees)?
  16. 16.In a right-angled triangle, one of the other two angles is 30°. What is the third angle (in degrees)?
  17. 17.An exterior angle of a triangle is 102°. One of its two interior opposite angles is 54°. What is the other one (in degrees)?
  18. 18.In a right-angled triangle, one of the other two angles is 67°. What is the third angle (in degrees)?
  19. 19.In a right-angled triangle, one of the other two angles is 27°. What is the third angle (in degrees)?
  20. 20.The two interior opposite angles of a triangle are 23° and 55°. What is the exterior angle (in degrees)?
  21. 21.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  22. 22.In a right-angled triangle, one of the other two angles is 68°. What is the third angle (in degrees)?
  23. 23.In triangle ABC, angle A = 91° and angle B = 33°. What is angle C (in degrees)?
  24. 24.Can a triangle have sides of 7 cm, 7 cm and 18 cm? (a) No (b) Yes
  25. 25.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  26. 26.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?
  27. 27.In a right-angled triangle, one of the other two angles is 31°. What is the third angle (in degrees)?
  28. 28.Can a triangle have sides of 5 cm, 5 cm and 15 cm? (a) No (b) Yes
  29. 29.An exterior angle of a triangle is 120°. One of its two interior opposite angles is 57°. What is the other one (in degrees)?
  30. 30.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  31. 31.Can a triangle have sides of 5 cm, 4 cm and 6 cm? (a) No (b) Yes
  32. 32.In triangle ABC, angle A = 56° and angle B = 47°. What is angle C (in degrees)?
  33. 33.The angles of a triangle are in the ratio 2 : 3 : 5. What is the smallest angle (in degrees)?
  34. 34.The angles of a triangle are in the ratio 3 : 3 : 4. What is the smallest angle (in degrees)?
  35. 35.In an isosceles triangle, the two equal angles are 25° each. What is the third angle (in degrees)?
  36. 36.The two interior opposite angles of a triangle are 31° and 22°. What is the exterior angle (in degrees)?
  37. 37.In an isosceles triangle, the two equal angles are 79° each. What is the third angle (in degrees)?
  38. 38.In a right-angled triangle, one of the other two angles is 48°. What is the third angle (in degrees)?
  39. 39.In an isosceles triangle, the angle between the two equal sides is 68°. What is each of the other two angles (in degrees)?
  40. 40.In triangle ABC, angle A = 82° and angle B = 61°. What is angle C (in degrees)?

Answer key

  1. No
  2. 126
  3. 96
  4. 26
  5. 4
  6. 61
  7. 66
  8. 63
  9. 45
  10. 12
  11. 90
  12. 30
  13. 39
  14. 32
  15. 41
  16. 60
  17. 48
  18. 23
  19. 63
  20. 78
  21. 100
  22. 22
  23. 56
  24. No
  25. 40
  26. 48
  27. 59
  28. No
  29. 63
  30. 72
  31. Yes
  32. 77
  33. 36
  34. 54
  35. 130
  36. 53
  37. 22
  38. 42
  39. 56
  40. 37

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