← 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 949 · 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 an isosceles triangle, the two equal angles are 76° each. What is the third angle (in degrees)?
  2. 2.In triangle ABC, angle A = 23° and angle B = 74°. What is angle C (in degrees)?
  3. 3.Can a triangle have sides of 5 cm, 12 cm and 13 cm? (a) Yes (b) No
  4. 4.Can a triangle have sides of 6 cm, 6 cm and 3 cm? (a) Yes (b) No
  5. 5.In an isosceles triangle, the angle between the two equal sides is 112°. What is each of the other two angles (in degrees)?
  6. 6.In a right-angled triangle, one of the other two angles is 59°. What is the third angle (in degrees)?
  7. 7.The two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  8. 8.Can a triangle have sides of 4 cm, 5 cm and 4 cm? (a) No (b) Yes
  9. 9.The two shorter sides of a right-angled triangle are 36 cm and 15 cm. How long is the longest side (in cm)?
  10. 10.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  11. 11.In triangle ABC, angle A = 91° and angle B = 22°. What is angle C (in degrees)?
  12. 12.In a right-angled triangle, one of the other two angles is 64°. What is the third angle (in degrees)?
  13. 13.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?
  14. 14.In a right-angled triangle, one of the other two angles is 22°. What is the third angle (in degrees)?
  15. 15.In a right-angled triangle, one of the other two angles is 54°. What is the third angle (in degrees)?
  16. 16.An exterior angle of a triangle is 57°. One of its two interior opposite angles is 34°. What is the other one (in degrees)?
  17. 17.The two shorter sides of a right-angled triangle are 5 cm and 12 cm. How long is the longest side (in cm)?
  18. 18.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  19. 19.In triangle ABC, angle A = 87° and angle B = 25°. What is angle C (in degrees)?
  20. 20.Can a triangle have sides of 9 cm, 3 cm and 3 cm? (a) Yes (b) No
  21. 21.An exterior angle of a triangle is 76°. One of its two interior opposite angles is 47°. What is the other one (in degrees)?
  22. 22.In a right-angled triangle, one of the other two angles is 51°. What is the third angle (in degrees)?
  23. 23.Can a triangle have sides of 6 cm, 16 cm and 6 cm? (a) No (b) Yes
  24. 24.The two shorter sides of a right-angled triangle are 12 cm and 5 cm. How long is the longest side (in cm)?
  25. 25.An exterior angle of a triangle is 88°. One of its two interior opposite angles is 20°. What is the other one (in degrees)?
  26. 26.In triangle ABC, angle A = 38° and angle B = 71°. What is angle C (in degrees)?
  27. 27.In a right-angled triangle, one of the other two angles is 79°. What is the third angle (in degrees)?
  28. 28.The two interior opposite angles of a triangle are 69° and 41°. What is the exterior angle (in degrees)?
  29. 29.The angles of a triangle are in the ratio 2 : 7 : 9. What is the biggest angle (in degrees)?
  30. 30.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  31. 31.In triangle ABC, angle A = 37° and angle B = 105°. What is angle C (in degrees)?
  32. 32.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (in degrees)?
  33. 33.In triangle ABC, angle A = 95° and angle B = 20°. What is angle C (in degrees)?
  34. 34.In triangle ABC, angle A = 27° and angle B = 51°. What is angle C (in degrees)?
  35. 35.Can a triangle have sides of 12 cm, 22 cm and 10 cm? (a) No (b) Yes
  36. 36.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)?
  37. 37.An exterior angle of a triangle is 145°. One of its two interior opposite angles is 70°. What is the other one (in degrees)?
  38. 38.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  39. 39.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)?
  40. 40.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?

Answer key

  1. 28
  2. 83
  3. Yes
  4. Yes
  5. 34
  6. 31
  7. 39
  8. Yes
  9. 39
  10. 100
  11. 67
  12. 26
  13. 50
  14. 68
  15. 36
  16. 23
  17. 13
  18. 100
  19. 68
  20. No
  21. 29
  22. 39
  23. No
  24. 13
  25. 68
  26. 71
  27. 11
  28. 110
  29. 90
  30. 17
  31. 38
  32. 72
  33. 65
  34. 102
  35. No
  36. 7
  37. 75
  38. 72
  39. 12
  40. 48

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