← 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 394 · 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 : 2 : 6. What is the smallest angle (in degrees)?
  2. 2.Can a triangle have sides of 11 cm, 14 cm and 9 cm? (a) No (b) Yes
  3. 3.In a right-angled triangle, one of the other two angles is 63°. What is the third angle (in degrees)?
  4. 4.The two interior opposite angles of a triangle are 28° and 73°. What is the exterior angle (in degrees)?
  5. 5.In a right-angled triangle, one of the other two angles is 26°. What is the third angle (in degrees)?
  6. 6.An exterior angle of a triangle is 78°. One of its two interior opposite angles is 29°. What is the other one (in degrees)?
  7. 7.Can a triangle have sides of 3 cm, 6 cm and 7 cm? (a) No (b) Yes
  8. 8.Can a triangle have sides of 10 cm, 10 cm and 23 cm? (a) Yes (b) No
  9. 9.In a right-angled triangle, one of the other two angles is 61°. What is the third angle (in degrees)?
  10. 10.Can a triangle have sides of 7 cm, 11 cm and 23 cm? (a) Yes (b) No
  11. 11.The angles of a triangle are in the ratio 2 : 2 : 5. What is the smallest angle (in degrees)?
  12. 12.In a right-angled triangle, one of the other two angles is 50°. What is the third angle (in degrees)?
  13. 13.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  14. 14.In triangle ABC, angle A = 93° and angle B = 65°. What is angle C (in degrees)?
  15. 15.In triangle ABC, angle A = 34° and angle B = 99°. What is angle C (in degrees)?
  16. 16.In triangle ABC, angle A = 99° and angle B = 43°. What is angle C (in degrees)?
  17. 17.Can a triangle have sides of 5 cm, 7 cm and 8 cm? (a) No (b) Yes
  18. 18.An exterior angle of a triangle is 112°. One of its two interior opposite angles is 77°. What is the other one (in degrees)?
  19. 19.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)?
  20. 20.The two shorter sides of a right-angled triangle are 24 cm and 18 cm. How long is the longest side (in cm)?
  21. 21.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  22. 22.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  23. 23.In an isosceles triangle, the two equal angles are 63° each. What is the third angle (in degrees)?
  24. 24.The two shorter sides of a right-angled triangle are 8 cm and 6 cm. How long is the longest side (in cm)?
  25. 25.In a right-angled triangle, one of the other two angles is 31°. What is the third angle (in degrees)?
  26. 26.The two shorter sides of a right-angled triangle are 24 cm and 10 cm. How long is the longest side (in cm)?
  27. 27.An exterior angle of a triangle is 104°. One of its two interior opposite angles is 39°. What is the other one (in degrees)?
  28. 28.An exterior angle of a triangle is 104°. One of its two interior opposite angles is 34°. What is the other one (in degrees)?
  29. 29.The two interior opposite angles of a triangle are 71° and 34°. What is the exterior angle (in degrees)?
  30. 30.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  31. 31.Can a triangle have sides of 11 cm, 22 cm and 8 cm? (a) No (b) Yes
  32. 32.In an isosceles triangle, the angle between the two equal sides is 106°. What is each of the other two angles (in degrees)?
  33. 33.The two shorter sides of a right-angled triangle are 9 cm and 12 cm. How long is the longest side (in cm)?
  34. 34.In a right-angled triangle, one of the other two angles is 15°. What is the third angle (in degrees)?
  35. 35.The longest side of a right-angled triangle is 15 cm and one of the other sides is 12 cm. How long is the third side (in cm)?
  36. 36.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  37. 37.In an isosceles triangle, the two equal angles are 40° each. What is the third angle (in degrees)?
  38. 38.An exterior angle of a triangle is 97°. One of its two interior opposite angles is 28°. What is the other one (in degrees)?
  39. 39.In a right-angled triangle, one of the other two angles is 39°. What is the third angle (in degrees)?
  40. 40.In an isosceles triangle, the angle between the two equal sides is 118°. What is each of the other two angles (in degrees)?

Answer key

  1. 20
  2. Yes
  3. 27
  4. 101
  5. 64
  6. 49
  7. Yes
  8. No
  9. 29
  10. No
  11. 40
  12. 40
  13. 45
  14. 22
  15. 47
  16. 38
  17. Yes
  18. 35
  19. 15
  20. 30
  21. 100
  22. 25
  23. 54
  24. 10
  25. 59
  26. 26
  27. 65
  28. 70
  29. 105
  30. 20
  31. No
  32. 37
  33. 15
  34. 75
  35. 9
  36. 25
  37. 100
  38. 69
  39. 51
  40. 31

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