← 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 504 · 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.An exterior angle of a triangle is 91°. One of its two interior opposite angles is 69°. What is the other one (in degrees)?
  2. 2.In an isosceles triangle, the angle between the two equal sides is 130°. What is each of the other two angles (in degrees)?
  3. 3.Can a triangle have sides of 4 cm, 6 cm and 11 cm? (a) No (b) Yes
  4. 4.In an isosceles triangle, the angle between the two equal sides is 86°. What is each of the other two angles (in degrees)?
  5. 5.The two interior opposite angles of a triangle are 64° and 34°. What is the exterior angle (in degrees)?
  6. 6.The two interior opposite angles of a triangle are 35° and 31°. What is the exterior angle (in degrees)?
  7. 7.Can a triangle have sides of 18 cm, 6 cm and 10 cm? (a) Yes (b) No
  8. 8.The two interior opposite angles of a triangle are 27° and 31°. What is the exterior angle (in degrees)?
  9. 9.In triangle ABC, angle A = 50° and angle B = 96°. What is angle C (in degrees)?
  10. 10.An exterior angle of a triangle is 57°. One of its two interior opposite angles is 26°. What is the other one (in degrees)?
  11. 11.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)?
  12. 12.The longest side of a right-angled triangle is 25 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  13. 13.In triangle ABC, angle A = 96° and angle B = 30°. What is angle C (in degrees)?
  14. 14.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  15. 15.In an isosceles triangle, the angle between the two equal sides is 150°. What is each of the other two angles (in degrees)?
  16. 16.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  17. 17.An exterior angle of a triangle is 78°. One of its two interior opposite angles is 21°. What is the other one (in degrees)?
  18. 18.In a right-angled triangle, one of the other two angles is 20°. What is the third angle (in degrees)?
  19. 19.An exterior angle of a triangle is 63°. One of its two interior opposite angles is 23°. What is the other one (in degrees)?
  20. 20.In triangle ABC, angle A = 87° and angle B = 25°. What is angle C (in degrees)?
  21. 21.The two interior opposite angles of a triangle are 56° and 22°. What is the exterior angle (in degrees)?
  22. 22.An exterior angle of a triangle is 83°. One of its two interior opposite angles is 61°. What is the other one (in degrees)?
  23. 23.An exterior angle of a triangle is 106°. One of its two interior opposite angles is 78°. What is the other one (in degrees)?
  24. 24.The angles of a triangle are in the ratio 1 : 2 : 6. What is the smallest angle (in degrees)?
  25. 25.The longest side of a right-angled triangle is 25 cm and one of the other sides is 24 cm. How long is the third side (in cm)?
  26. 26.The angles of a triangle are in the ratio 1 : 2 : 2. What is the biggest angle (in degrees)?
  27. 27.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)?
  28. 28.In triangle ABC, angle A = 47° and angle B = 99°. What is angle C (in degrees)?
  29. 29.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  30. 30.The two interior opposite angles of a triangle are 80° and 60°. What is the exterior angle (in degrees)?
  31. 31.The two interior opposite angles of a triangle are 56° and 49°. What is the exterior angle (in degrees)?
  32. 32.In a right-angled triangle, one of the other two angles is 47°. What is the third angle (in degrees)?
  33. 33.Can a triangle have sides of 10 cm, 2 cm and 12 cm? (a) No (b) Yes
  34. 34.In a right-angled triangle, one of the other two angles is 54°. What is the third angle (in degrees)?
  35. 35.The two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  36. 36.An exterior angle of a triangle is 58°. One of its two interior opposite angles is 32°. What is the other one (in degrees)?
  37. 37.In an isosceles triangle, the angle between the two equal sides is 158°. What is each of the other two angles (in degrees)?
  38. 38.Can a triangle have sides of 12 cm, 17 cm and 5 cm? (a) Yes (b) No
  39. 39.In triangle ABC, angle A = 77° and angle B = 50°. What is angle C (in degrees)?
  40. 40.The two interior opposite angles of a triangle are 25° and 62°. What is the exterior angle (in degrees)?

Answer key

  1. 22
  2. 25
  3. No
  4. 47
  5. 98
  6. 66
  7. No
  8. 58
  9. 34
  10. 31
  11. 12
  12. 20
  13. 54
  14. 25
  15. 15
  16. 90
  17. 57
  18. 70
  19. 40
  20. 68
  21. 78
  22. 22
  23. 28
  24. 20
  25. 7
  26. 72
  27. 24
  28. 34
  29. 17
  30. 140
  31. 105
  32. 43
  33. No
  34. 36
  35. 39
  36. 26
  37. 11
  38. No
  39. 53
  40. 87

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