← 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 788 · 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.In a right-angled triangle, one of the other two angles is 31°. What is the third angle (in degrees)?
  2. 2.The two shorter sides of a right-angled triangle are 24 cm and 18 cm. How long is the longest side (in cm)?
  3. 3.The two shorter sides of a right-angled triangle are 12 cm and 16 cm. How long is the longest side (in cm)?
  4. 4.The angles of a triangle are in the ratio 1 : 2 : 2. What is the smallest angle (in degrees)?
  5. 5.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  6. 6.In triangle ABC, angle A = 83° and angle B = 43°. What is angle C (in degrees)?
  7. 7.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  8. 8.In a right-angled triangle, one of the other two angles is 29°. What is the third angle (in degrees)?
  9. 9.In a right-angled triangle, one of the other two angles is 76°. What is the third angle (in degrees)?
  10. 10.An exterior angle of a triangle is 118°. One of its two interior opposite angles is 47°. What is the other one (in degrees)?
  11. 11.In a right-angled triangle, one of the other two angles is 67°. What is the third angle (in degrees)?
  12. 12.In a right-angled triangle, one of the other two angles is 68°. What is the third angle (in degrees)?
  13. 13.Can a triangle have sides of 4 cm, 5 cm and 11 cm? (a) No (b) Yes
  14. 14.Can a triangle have sides of 25 cm, 10 cm and 10 cm? (a) No (b) Yes
  15. 15.In triangle ABC, angle A = 22° and angle B = 135°. What is angle C (in degrees)?
  16. 16.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  17. 17.In a right-angled triangle, one of the other two angles is 26°. What is the third angle (in degrees)?
  18. 18.In triangle ABC, angle A = 49° and angle B = 93°. What is angle C (in degrees)?
  19. 19.The two interior opposite angles of a triangle are 30° and 28°. What is the exterior angle (in degrees)?
  20. 20.In triangle ABC, angle A = 96° and angle B = 57°. What is angle C (in degrees)?
  21. 21.In triangle ABC, angle A = 36° and angle B = 32°. What is angle C (in degrees)?
  22. 22.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  23. 23.In a right-angled triangle, one of the other two angles is 16°. What is the third angle (in degrees)?
  24. 24.The two interior opposite angles of a triangle are 65° and 59°. What is the exterior angle (in degrees)?
  25. 25.Can a triangle have sides of 9 cm, 9 cm and 18 cm? (a) Yes (b) No
  26. 26.Can a triangle have sides of 7 cm, 9 cm and 6 cm? (a) No (b) Yes
  27. 27.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)?
  28. 28.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  29. 29.In an isosceles triangle, the angle between the two equal sides is 52°. What is each of the other two angles (in degrees)?
  30. 30.In a right-angled triangle, one of the other two angles is 72°. What is the third angle (in degrees)?
  31. 31.In triangle ABC, angle A = 66° and angle B = 82°. What is angle C (in degrees)?
  32. 32.The two shorter sides of a right-angled triangle are 18 cm and 24 cm. How long is the longest side (in cm)?
  33. 33.An exterior angle of a triangle is 85°. One of its two interior opposite angles is 51°. What is the other one (in degrees)?
  34. 34.In a right-angled triangle, one of the other two angles is 18°. What is the third angle (in degrees)?
  35. 35.The longest side of a right-angled triangle is 39 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  36. 36.The two shorter sides of a right-angled triangle are 12 cm and 5 cm. How long is the longest side (in cm)?
  37. 37.In a right-angled triangle, one of the other two angles is 66°. What is the third angle (in degrees)?
  38. 38.In an isosceles triangle, the two equal angles are 30° each. What is the third angle (in degrees)?
  39. 39.The two shorter sides of a right-angled triangle are 4 cm and 3 cm. How long is the longest side (in cm)?
  40. 40.In a right-angled triangle, one of the other two angles is 45°. What is the third angle (in degrees)?

Answer key

  1. 59
  2. 30
  3. 20
  4. 36
  5. 90
  6. 54
  7. 36
  8. 61
  9. 14
  10. 71
  11. 23
  12. 22
  13. No
  14. No
  15. 23
  16. 100
  17. 64
  18. 38
  19. 58
  20. 27
  21. 112
  22. 45
  23. 74
  24. 124
  25. No
  26. Yes
  27. 3
  28. 90
  29. 64
  30. 18
  31. 32
  32. 30
  33. 34
  34. 72
  35. 36
  36. 13
  37. 24
  38. 120
  39. 5
  40. 45

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