← 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 478 · 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 8 cm, 5 cm and 4 cm? (a) Yes (b) No
  2. 2.Can a triangle have sides of 22 cm, 10 cm and 9 cm? (a) No (b) Yes
  3. 3.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  4. 4.In an isosceles triangle, the angle between the two equal sides is 96°. What is each of the other two angles (in degrees)?
  5. 5.In triangle ABC, angle A = 66° and angle B = 35°. What is angle C (in degrees)?
  6. 6.In a right-angled triangle, one of the other two angles is 48°. What is the third angle (in degrees)?
  7. 7.In a right-angled triangle, one of the other two angles is 76°. What is the third angle (in degrees)?
  8. 8.Can a triangle have sides of 12 cm, 3 cm and 14 cm? (a) No (b) Yes
  9. 9.In a right-angled triangle, one of the other two angles is 19°. What is the third angle (in degrees)?
  10. 10.Can a triangle have sides of 12 cm, 6 cm and 7 cm? (a) No (b) Yes
  11. 11.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)?
  12. 12.The longest side of a right-angled triangle is 10 cm and one of the other sides is 6 cm. How long is the third side (in cm)?
  13. 13.Can a triangle have sides of 25 cm, 10 cm and 10 cm? (a) Yes (b) No
  14. 14.The two shorter sides of a right-angled triangle are 15 cm and 20 cm. How long is the longest side (in cm)?
  15. 15.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)?
  16. 16.In an isosceles triangle, the two equal angles are 78° each. What is the third angle (in degrees)?
  17. 17.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)?
  18. 18.In an isosceles triangle, the two equal angles are 73° each. What is the third angle (in degrees)?
  19. 19.The two interior opposite angles of a triangle are 29° and 66°. What is the exterior angle (in degrees)?
  20. 20.In triangle ABC, angle A = 43° and angle B = 56°. What is angle C (in degrees)?
  21. 21.The two interior opposite angles of a triangle are 58° and 76°. What is the exterior angle (in degrees)?
  22. 22.In triangle ABC, angle A = 71° and angle B = 38°. What is angle C (in degrees)?
  23. 23.In triangle ABC, angle A = 29° and angle B = 31°. What is angle C (in degrees)?
  24. 24.The longest side of a right-angled triangle is 10 cm and one of the other sides is 8 cm. How long is the third side (in cm)?
  25. 25.An exterior angle of a triangle is 112°. One of its two interior opposite angles is 69°. What is the other one (in degrees)?
  26. 26.In triangle ABC, angle A = 54° and angle B = 97°. What is angle C (in degrees)?
  27. 27.In a right-angled triangle, one of the other two angles is 23°. What is the third angle (in degrees)?
  28. 28.In an isosceles triangle, the two equal angles are 45° each. What is the third angle (in degrees)?
  29. 29.The two interior opposite angles of a triangle are 25° and 29°. What is the exterior angle (in degrees)?
  30. 30.In a right-angled triangle, one of the other two angles is 13°. What is the third angle (in degrees)?
  31. 31.In an isosceles triangle, the two equal angles are 69° each. What is the third angle (in degrees)?
  32. 32.In triangle ABC, angle A = 68° and angle B = 62°. What is angle C (in degrees)?
  33. 33.In an isosceles triangle, the angle between the two equal sides is 54°. What is each of the other two angles (in degrees)?
  34. 34.In a right-angled triangle, one of the other two angles is 54°. What is the third angle (in degrees)?
  35. 35.In triangle ABC, angle A = 58° and angle B = 91°. What is angle C (in degrees)?
  36. 36.In triangle ABC, angle A = 87° and angle B = 32°. What is angle C (in degrees)?
  37. 37.The two shorter sides of a right-angled triangle are 36 cm and 15 cm. How long is the longest side (in cm)?
  38. 38.In an isosceles triangle, the angle between the two equal sides is 84°. What is each of the other two angles (in degrees)?
  39. 39.An exterior angle of a triangle is 56°. One of its two interior opposite angles is 34°. What is the other one (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 17°. What is the third angle (in degrees)?

Answer key

  1. Yes
  2. No
  3. 18
  4. 42
  5. 79
  6. 42
  7. 14
  8. Yes
  9. 71
  10. Yes
  11. 4
  12. 8
  13. No
  14. 25
  15. 3
  16. 24
  17. 8
  18. 34
  19. 95
  20. 81
  21. 134
  22. 71
  23. 120
  24. 6
  25. 43
  26. 29
  27. 67
  28. 90
  29. 54
  30. 77
  31. 42
  32. 50
  33. 63
  34. 36
  35. 31
  36. 61
  37. 39
  38. 48
  39. 22
  40. 73

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