← 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 404 · 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 113°. One of its two interior opposite angles is 67°. What is the other one (in degrees)?
  2. 2.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  3. 3.In an isosceles triangle, the two equal angles are 50° each. What is the third angle (in degrees)?
  4. 4.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  5. 5.In triangle ABC, angle A = 61° and angle B = 78°. What is angle C (in degrees)?
  6. 6.The two interior opposite angles of a triangle are 36° and 78°. What is the exterior angle (in degrees)?
  7. 7.Can a triangle have sides of 11 cm, 13 cm and 8 cm? (a) No (b) Yes
  8. 8.The angles of a triangle are in the ratio 2 : 2 : 5. What is the smallest angle (in degrees)?
  9. 9.In a right-angled triangle, one of the other two angles is 80°. What is the third angle (in degrees)?
  10. 10.In a right-angled triangle, one of the other two angles is 58°. What is the third angle (in degrees)?
  11. 11.An exterior angle of a triangle is 105°. One of its two interior opposite angles is 79°. What is the other one (in degrees)?
  12. 12.In an isosceles triangle, the two equal angles are 47° each. What is the third angle (in degrees)?
  13. 13.An exterior angle of a triangle is 50°. One of its two interior opposite angles is 26°. What is the other one (in degrees)?
  14. 14.Can a triangle have sides of 17 cm, 9 cm and 7 cm? (a) Yes (b) No
  15. 15.The two shorter sides of a right-angled triangle are 36 cm and 15 cm. How long is the longest side (in cm)?
  16. 16.In triangle ABC, angle A = 80° and angle B = 20°. What is angle C (in degrees)?
  17. 17.In an isosceles triangle, the angle between the two equal sides is 108°. What is each of the other two angles (in degrees)?
  18. 18.The two interior opposite angles of a triangle are 22° and 49°. What is the exterior angle (in degrees)?
  19. 19.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  20. 20.The two interior opposite angles of a triangle are 80° and 32°. What is the exterior angle (in degrees)?
  21. 21.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)?
  22. 22.In a right-angled triangle, one of the other two angles is 33°. What is the third angle (in degrees)?
  23. 23.The two shorter sides of a right-angled triangle are 10 cm and 24 cm. How long is the longest side (in cm)?
  24. 24.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  25. 25.The two interior opposite angles of a triangle are 24° and 28°. What is the exterior angle (in degrees)?
  26. 26.The longest side of a right-angled triangle is 13 cm and one of the other sides is 5 cm. How long is the third side (in cm)?
  27. 27.Can a triangle have sides of 23 cm, 9 cm and 11 cm? (a) Yes (b) No
  28. 28.Can a triangle have sides of 4 cm, 8 cm and 8 cm? (a) No (b) Yes
  29. 29.The two shorter sides of a right-angled triangle are 12 cm and 16 cm. How long is the longest side (in cm)?
  30. 30.In an isosceles triangle, the two equal angles are 61° each. What is the third angle (in degrees)?
  31. 31.Can a triangle have sides of 10 cm, 6 cm and 19 cm? (a) Yes (b) No
  32. 32.In triangle ABC, angle A = 32° and angle B = 48°. What is angle C (in degrees)?
  33. 33.An exterior angle of a triangle is 149°. One of its two interior opposite angles is 72°. What is the other one (in degrees)?
  34. 34.The angles of a triangle are in the ratio 1 : 2 : 3. What is the smallest angle (in degrees)?
  35. 35.In a right-angled triangle, one of the other two angles is 24°. What is the third angle (in degrees)?
  36. 36.Can a triangle have sides of 7 cm, 20 cm and 8 cm? (a) Yes (b) No
  37. 37.In an isosceles triangle, the two equal angles are 84° each. What is the third angle (in degrees)?
  38. 38.In triangle ABC, angle A = 83° and angle B = 57°. What is angle C (in degrees)?
  39. 39.In a right-angled triangle, one of the other two angles is 26°. What is the third angle (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 55°. What is the third angle (in degrees)?

Answer key

  1. 46
  2. 25
  3. 80
  4. 45
  5. 41
  6. 114
  7. Yes
  8. 40
  9. 10
  10. 32
  11. 26
  12. 86
  13. 24
  14. No
  15. 39
  16. 80
  17. 36
  18. 71
  19. 25
  20. 112
  21. 15
  22. 57
  23. 26
  24. 20
  25. 52
  26. 12
  27. No
  28. Yes
  29. 20
  30. 58
  31. No
  32. 100
  33. 77
  34. 30
  35. 66
  36. No
  37. 12
  38. 40
  39. 64
  40. 35

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