← 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 297 · 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 longest side of a right-angled triangle is 5 cm and one of the other sides is 4 cm. How long is the third side (in cm)?
  2. 2.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  3. 3.An exterior angle of a triangle is 114°. One of its two interior opposite angles is 73°. What is the other one (in degrees)?
  4. 4.In triangle ABC, angle A = 67° and angle B = 87°. What is angle C (in degrees)?
  5. 5.Can a triangle have sides of 10 cm, 11 cm and 6 cm? (a) No (b) Yes
  6. 6.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?
  7. 7.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  8. 8.An exterior angle of a triangle is 142°. One of its two interior opposite angles is 62°. What is the other one (in degrees)?
  9. 9.In an isosceles triangle, the two equal angles are 45° each. What is the third angle (in degrees)?
  10. 10.In a right-angled triangle, one of the other two angles is 26°. What is the third angle (in degrees)?
  11. 11.An exterior angle of a triangle is 107°. One of its two interior opposite angles is 41°. What is the other one (in degrees)?
  12. 12.In a right-angled triangle, one of the other two angles is 11°. What is the third angle (in degrees)?
  13. 13.In triangle ABC, angle A = 87° and angle B = 49°. What is angle C (in degrees)?
  14. 14.In an isosceles triangle, the two equal angles are 76° each. What is the third angle (in degrees)?
  15. 15.In an isosceles triangle, the angle between the two equal sides is 88°. What is each of the other two angles (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.Can a triangle have sides of 9 cm, 11 cm and 3 cm? (a) No (b) Yes
  18. 18.In an isosceles triangle, the two equal angles are 78° each. What is the third angle (in degrees)?
  19. 19.In an isosceles triangle, the angle between the two equal sides is 64°. What is each of the other two angles (in degrees)?
  20. 20.In triangle ABC, angle A = 38° and angle B = 121°. What is angle C (in degrees)?
  21. 21.Can a triangle have sides of 5 cm, 7 cm and 5 cm? (a) Yes (b) No
  22. 22.Can a triangle have sides of 9 cm, 11 cm and 11 cm? (a) Yes (b) No
  23. 23.In an isosceles triangle, the two equal angles are 33° each. What is the third angle (in degrees)?
  24. 24.In an isosceles triangle, the two equal angles are 40° each. What is the third angle (in degrees)?
  25. 25.In a right-angled triangle, one of the other two angles is 50°. What is the third angle (in degrees)?
  26. 26.In an isosceles triangle, the two equal angles are 37° each. What is the third angle (in degrees)?
  27. 27.The two interior opposite angles of a triangle are 52° and 54°. What is the exterior angle (in degrees)?
  28. 28.An exterior angle of a triangle is 81°. One of its two interior opposite angles is 47°. What is the other one (in degrees)?
  29. 29.In triangle ABC, angle A = 70° and angle B = 38°. What is angle C (in degrees)?
  30. 30.An exterior angle of a triangle is 94°. One of its two interior opposite angles is 48°. What is the other one (in degrees)?
  31. 31.In a right-angled triangle, one of the other two angles is 61°. What is the third angle (in degrees)?
  32. 32.An exterior angle of a triangle is 127°. One of its two interior opposite angles is 51°. What is the other one (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.Can a triangle have sides of 4 cm, 7 cm and 16 cm? (a) No (b) Yes
  35. 35.Can a triangle have sides of 8 cm, 2 cm and 2 cm? (a) No (b) Yes
  36. 36.In a right-angled triangle, one of the other two angles is 33°. What is the third angle (in degrees)?
  37. 37.In triangle ABC, angle A = 86° and angle B = 56°. What is angle C (in degrees)?
  38. 38.In triangle ABC, angle A = 33° and angle B = 50°. What is angle C (in degrees)?
  39. 39.An exterior angle of a triangle is 106°. One of its two interior opposite angles is 77°. What is the other one (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 52°. What is the third angle (in degrees)?

Answer key

  1. 3
  2. 25
  3. 41
  4. 26
  5. Yes
  6. 50
  7. 90
  8. 80
  9. 90
  10. 64
  11. 66
  12. 79
  13. 44
  14. 28
  15. 46
  16. 100
  17. Yes
  18. 24
  19. 58
  20. 21
  21. Yes
  22. Yes
  23. 114
  24. 100
  25. 40
  26. 106
  27. 106
  28. 34
  29. 72
  30. 46
  31. 29
  32. 76
  33. 27
  34. No
  35. No
  36. 57
  37. 38
  38. 97
  39. 29
  40. 38

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