← 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 690 · 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 angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  2. 2.In a right-angled triangle, one of the other two angles is 44°. What is the third angle (in degrees)?
  3. 3.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  4. 4.The two shorter sides of a right-angled triangle are 12 cm and 16 cm. How long is the longest side (in cm)?
  5. 5.In triangle ABC, angle A = 31° and angle B = 42°. What is angle C (in degrees)?
  6. 6.The two interior opposite angles of a triangle are 72° and 41°. What is the exterior angle (in degrees)?
  7. 7.The two interior opposite angles of a triangle are 27° and 70°. What is the exterior angle (in degrees)?
  8. 8.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  9. 9.The angles of a triangle are in the ratio 2 : 3 : 5. What is the smallest angle (in degrees)?
  10. 10.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  11. 11.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  12. 12.In an isosceles triangle, the two equal angles are 45° each. What is the third angle (in degrees)?
  13. 13.In triangle ABC, angle A = 49° and angle B = 51°. What is angle C (in degrees)?
  14. 14.Can a triangle have sides of 10 cm, 10 cm and 7 cm? (a) Yes (b) No
  15. 15.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)?
  16. 16.In triangle ABC, angle A = 76° and angle B = 75°. What is angle C (in degrees)?
  17. 17.In triangle ABC, angle A = 34° and angle B = 84°. What is angle C (in degrees)?
  18. 18.In a right-angled triangle, one of the other two angles is 14°. What is the third angle (in degrees)?
  19. 19.Can a triangle have sides of 11 cm, 10 cm and 2 cm? (a) No (b) Yes
  20. 20.In a right-angled triangle, one of the other two angles is 67°. What is the third angle (in degrees)?
  21. 21.In an isosceles triangle, the two equal angles are 30° each. What is the third angle (in degrees)?
  22. 22.In a right-angled triangle, one of the other two angles is 50°. What is the third angle (in degrees)?
  23. 23.In triangle ABC, angle A = 84° and angle B = 34°. What is angle C (in degrees)?
  24. 24.The angles of a triangle are in the ratio 2 : 7 : 9. What is the biggest angle (in degrees)?
  25. 25.The angles of a triangle are in the ratio 3 : 5 : 7. What is the biggest angle (in degrees)?
  26. 26.In triangle ABC, angle A = 54° and angle B = 36°. What is angle C (in degrees)?
  27. 27.In a right-angled triangle, one of the other two angles is 74°. What is the third angle (in degrees)?
  28. 28.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  29. 29.In a right-angled triangle, one of the other two angles is 47°. What is the third angle (in degrees)?
  30. 30.In a right-angled triangle, one of the other two angles is 45°. What is the third angle (in degrees)?
  31. 31.In an isosceles triangle, the two equal angles are 70° each. What is the third angle (in degrees)?
  32. 32.The longest side of a right-angled triangle is 25 cm and one of the other sides is 20 cm. How long is the third side (in cm)?
  33. 33.In an isosceles triangle, the angle between the two equal sides is 28°. What is each of the other two angles (in degrees)?
  34. 34.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  35. 35.In an isosceles triangle, the two equal angles are 21° each. What is the third angle (in degrees)?
  36. 36.Can a triangle have sides of 8 cm, 10 cm and 13 cm? (a) No (b) Yes
  37. 37.In a right-angled triangle, one of the other two angles is 46°. What is the third angle (in degrees)?
  38. 38.In triangle ABC, angle A = 24° and angle B = 81°. What is angle C (in degrees)?
  39. 39.In an isosceles triangle, the two equal angles are 80° each. What is the third angle (in degrees)?
  40. 40.In triangle ABC, angle A = 100° and angle B = 43°. What is angle C (in degrees)?

Answer key

  1. 90
  2. 46
  3. 25
  4. 20
  5. 107
  6. 113
  7. 97
  8. 20
  9. 36
  10. 17
  11. 120
  12. 90
  13. 80
  14. Yes
  15. 15
  16. 29
  17. 62
  18. 76
  19. Yes
  20. 23
  21. 120
  22. 40
  23. 62
  24. 90
  25. 84
  26. 90
  27. 16
  28. 90
  29. 43
  30. 45
  31. 40
  32. 15
  33. 76
  34. 18
  35. 138
  36. Yes
  37. 44
  38. 75
  39. 20
  40. 37

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