← 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 605 · 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.Can a triangle have sides of 9 cm, 9 cm and 15 cm? (a) Yes (b) No
  2. 2.In a right-angled triangle, one of the other two angles is 46°. What is the third angle (in degrees)?
  3. 3.In a right-angled triangle, one of the other two angles is 28°. What is the third angle (in degrees)?
  4. 4.The angles of a triangle are in the ratio 1 : 1 : 2. What is the smallest angle (in degrees)?
  5. 5.In triangle ABC, angle A = 26° and angle B = 42°. What is angle C (in degrees)?
  6. 6.The two interior opposite angles of a triangle are 75° and 35°. What is the exterior angle (in degrees)?
  7. 7.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  8. 8.In an isosceles triangle, the two equal angles are 50° each. What is the third angle (in degrees)?
  9. 9.The angles of a triangle are in the ratio 2 : 7 : 9. What is the biggest angle (in degrees)?
  10. 10.An exterior angle of a triangle is 99°. One of its two interior opposite angles is 67°. What is the other one (in degrees)?
  11. 11.Can a triangle have sides of 7 cm, 8 cm and 18 cm? (a) Yes (b) No
  12. 12.An exterior angle of a triangle is 91°. One of its two interior opposite angles is 51°. What is the other one (in degrees)?
  13. 13.Can a triangle have sides of 10 cm, 3 cm and 8 cm? (a) Yes (b) No
  14. 14.The two interior opposite angles of a triangle are 62° and 71°. What is the exterior angle (in degrees)?
  15. 15.In an isosceles triangle, the two equal angles are 47° each. What is the third angle (in degrees)?
  16. 16.The two interior opposite angles of a triangle are 48° and 49°. What is the exterior angle (in degrees)?
  17. 17.The two shorter sides of a right-angled triangle are 20 cm and 15 cm. How long is the longest side (in cm)?
  18. 18.Can a triangle have sides of 11 cm, 9 cm and 16 cm? (a) Yes (b) No
  19. 19.In a right-angled triangle, one of the other two angles is 62°. What is the third angle (in degrees)?
  20. 20.An exterior angle of a triangle is 47°. One of its two interior opposite angles is 27°. What is the other one (in degrees)?
  21. 21.In triangle ABC, angle A = 24° and angle B = 126°. What is angle C (in degrees)?
  22. 22.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?
  23. 23.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  24. 24.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)?
  25. 25.In a right-angled triangle, one of the other two angles is 58°. What is the third angle (in degrees)?
  26. 26.In triangle ABC, angle A = 65° and angle B = 57°. What is angle C (in degrees)?
  27. 27.An exterior angle of a triangle is 142°. One of its two interior opposite angles is 70°. What is the other one (in degrees)?
  28. 28.An exterior angle of a triangle is 50°. One of its two interior opposite angles is 28°. What is the other one (in degrees)?
  29. 29.In an isosceles triangle, the two equal angles are 43° each. What is the third angle (in degrees)?
  30. 30.The two interior opposite angles of a triangle are 60° and 33°. What is the exterior angle (in degrees)?
  31. 31.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (in degrees)?
  32. 32.An exterior angle of a triangle is 63°. One of its two interior opposite angles is 41°. What is the other one (in degrees)?
  33. 33.In triangle ABC, angle A = 58° and angle B = 76°. What is angle C (in degrees)?
  34. 34.In an isosceles triangle, the two equal angles are 63° each. What is the third angle (in degrees)?
  35. 35.Can a triangle have sides of 25 cm, 8 cm and 12 cm? (a) Yes (b) No
  36. 36.In triangle ABC, angle A = 56° and angle B = 40°. What is angle C (in degrees)?
  37. 37.Can a triangle have sides of 4 cm, 4 cm and 3 cm? (a) Yes (b) No
  38. 38.In triangle ABC, angle A = 78° and angle B = 28°. What is angle C (in degrees)?
  39. 39.The longest side of a right-angled triangle is 26 cm and one of the other sides is 10 cm. How long is the third side (in cm)?
  40. 40.Can a triangle have sides of 21 cm, 9 cm and 9 cm? (a) Yes (b) No

Answer key

  1. Yes
  2. 44
  3. 62
  4. 45
  5. 112
  6. 110
  7. 20
  8. 80
  9. 90
  10. 32
  11. No
  12. 40
  13. Yes
  14. 133
  15. 86
  16. 97
  17. 25
  18. Yes
  19. 28
  20. 20
  21. 30
  22. 48
  23. 17
  24. 20
  25. 32
  26. 58
  27. 72
  28. 22
  29. 94
  30. 93
  31. 72
  32. 22
  33. 46
  34. 54
  35. No
  36. 84
  37. Yes
  38. 74
  39. 24
  40. No

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