← 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 918 · 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 23 cm, 9 cm and 11 cm? (a) No (b) Yes
  2. 2.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  3. 3.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)?
  4. 4.Can a triangle have sides of 20 cm, 8 cm and 9 cm? (a) Yes (b) No
  5. 5.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  6. 6.Can a triangle have sides of 10 cm, 21 cm and 10 cm? (a) Yes (b) No
  7. 7.The two interior opposite angles of a triangle are 50° and 60°. What is the exterior angle (in degrees)?
  8. 8.The longest side of a right-angled triangle is 17 cm and one of the other sides is 8 cm. How long is the third side (in cm)?
  9. 9.In a right-angled triangle, one of the other two angles is 14°. What is the third angle (in degrees)?
  10. 10.An exterior angle of a triangle is 102°. One of its two interior opposite angles is 25°. What is the other one (in degrees)?
  11. 11.In triangle ABC, angle A = 71° and angle B = 66°. What is angle C (in degrees)?
  12. 12.An exterior angle of a triangle is 78°. One of its two interior opposite angles is 26°. What is the other one (in degrees)?
  13. 13.In an isosceles triangle, the two equal angles are 55° each. What is the third angle (in degrees)?
  14. 14.In a right-angled triangle, one of the other two angles is 34°. What is the third angle (in degrees)?
  15. 15.In an isosceles triangle, the two equal angles are 30° each. What is the third angle (in degrees)?
  16. 16.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (in degrees)?
  17. 17.An exterior angle of a triangle is 112°. One of its two interior opposite angles is 33°. What is the other one (in degrees)?
  18. 18.An exterior angle of a triangle is 89°. One of its two interior opposite angles is 31°. What is the other one (in degrees)?
  19. 19.An exterior angle of a triangle is 86°. One of its two interior opposite angles is 57°. What is the other one (in degrees)?
  20. 20.In triangle ABC, angle A = 20° and angle B = 133°. What is angle C (in degrees)?
  21. 21.In an isosceles triangle, the angle between the two equal sides is 140°. What is each of the other two angles (in degrees)?
  22. 22.The two interior opposite angles of a triangle are 75° and 34°. What is the exterior angle (in degrees)?
  23. 23.An exterior angle of a triangle is 76°. One of its two interior opposite angles is 28°. What is the other one (in degrees)?
  24. 24.In an isosceles triangle, the two equal angles are 21° each. What is the third angle (in degrees)?
  25. 25.In an isosceles triangle, the angle between the two equal sides is 126°. What is each of the other two angles (in degrees)?
  26. 26.The two interior opposite angles of a triangle are 24° and 55°. What is the exterior angle (in degrees)?
  27. 27.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  28. 28.In an isosceles triangle, the angle between the two equal sides is 46°. What is each of the other two angles (in degrees)?
  29. 29.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)?
  30. 30.In triangle ABC, angle A = 32° and angle B = 89°. What is angle C (in degrees)?
  31. 31.In triangle ABC, angle A = 46° and angle B = 42°. What is angle C (in degrees)?
  32. 32.In a right-angled triangle, one of the other two angles is 17°. What is the third angle (in degrees)?
  33. 33.In an isosceles triangle, the two equal angles are 64° each. What is the third angle (in degrees)?
  34. 34.Can a triangle have sides of 8 cm, 15 cm and 11 cm? (a) No (b) Yes
  35. 35.The two interior opposite angles of a triangle are 80° and 58°. What is the exterior angle (in degrees)?
  36. 36.In triangle ABC, angle A = 29° and angle B = 108°. What is angle C (in degrees)?
  37. 37.Can a triangle have sides of 4 cm, 3 cm and 3 cm? (a) Yes (b) No
  38. 38.In an isosceles triangle, the two equal angles are 56° each. What is the third angle (in degrees)?
  39. 39.In a right-angled triangle, one of the other two angles is 59°. What is the third angle (in degrees)?
  40. 40.An exterior angle of a triangle is 97°. One of its two interior opposite angles is 48°. What is the other one (in degrees)?

Answer key

  1. No
  2. 90
  3. 24
  4. No
  5. 17
  6. No
  7. 110
  8. 15
  9. 76
  10. 77
  11. 43
  12. 52
  13. 70
  14. 56
  15. 120
  16. 72
  17. 79
  18. 58
  19. 29
  20. 27
  21. 20
  22. 109
  23. 48
  24. 138
  25. 27
  26. 79
  27. 100
  28. 67
  29. 12
  30. 59
  31. 92
  32. 73
  33. 52
  34. Yes
  35. 138
  36. 43
  37. Yes
  38. 68
  39. 31
  40. 49

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