← 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 303 · 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 a right-angled triangle, one of the other two angles is 26°. What is the third angle (in degrees)?
  2. 2.In a right-angled triangle, one of the other two angles is 77°. What is the third angle (in degrees)?
  3. 3.In triangle ABC, angle A = 56° and angle B = 98°. What is angle C (in degrees)?
  4. 4.In an isosceles triangle, the two equal angles are 20° each. What is the third angle (in degrees)?
  5. 5.In a right-angled triangle, one of the other two angles is 24°. What is the third angle (in degrees)?
  6. 6.An exterior angle of a triangle is 117°. One of its two interior opposite angles is 47°. What is the other one (in degrees)?
  7. 7.In triangle ABC, angle A = 58° and angle B = 73°. What is angle C (in degrees)?
  8. 8.The two interior opposite angles of a triangle are 64° and 49°. What is the exterior angle (in degrees)?
  9. 9.In triangle ABC, angle A = 37° and angle B = 95°. What is angle C (in degrees)?
  10. 10.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  11. 11.In an isosceles triangle, the angle between the two equal sides is 32°. What is each of the other two angles (in degrees)?
  12. 12.The longest side of a right-angled triangle is 17 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  13. 13.In an isosceles triangle, the two equal angles are 56° each. What is the third angle (in degrees)?
  14. 14.In an isosceles triangle, the angle between the two equal sides is 34°. What is each of the other two angles (in degrees)?
  15. 15.The angles of a triangle are in the ratio 1 : 2 : 3. What is the smallest angle (in degrees)?
  16. 16.In triangle ABC, angle A = 93° and angle B = 40°. What is angle C (in degrees)?
  17. 17.The angles of a triangle are in the ratio 1 : 2 : 2. What is the biggest angle (in degrees)?
  18. 18.Can a triangle have sides of 2 cm, 9 cm and 2 cm? (a) No (b) Yes
  19. 19.In a right-angled triangle, one of the other two angles is 14°. What is the third angle (in degrees)?
  20. 20.The angles of a triangle are in the ratio 1 : 2 : 2. What is the smallest angle (in degrees)?
  21. 21.In a right-angled triangle, one of the other two angles is 79°. What is the third angle (in degrees)?
  22. 22.In an isosceles triangle, the two equal angles are 22° each. What is the third angle (in degrees)?
  23. 23.The two shorter sides of a right-angled triangle are 5 cm and 12 cm. How long is the longest side (in cm)?
  24. 24.Can a triangle have sides of 4 cm, 5 cm and 6 cm? (a) Yes (b) No
  25. 25.The two interior opposite angles of a triangle are 32° and 78°. What is the exterior angle (in degrees)?
  26. 26.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  27. 27.In an isosceles triangle, the angle between the two equal sides is 56°. What is each of the other two angles (in degrees)?
  28. 28.Can a triangle have sides of 8 cm, 7 cm and 4 cm? (a) Yes (b) No
  29. 29.In triangle ABC, angle A = 44° and angle B = 49°. What is angle C (in degrees)?
  30. 30.In triangle ABC, angle A = 56° and angle B = 61°. What is angle C (in degrees)?
  31. 31.Can a triangle have sides of 18 cm, 10 cm and 8 cm? (a) No (b) Yes
  32. 32.In triangle ABC, angle A = 90° and angle B = 52°. What is angle C (in degrees)?
  33. 33.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?
  34. 34.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?
  35. 35.The longest side of a right-angled triangle is 5 cm and one of the other sides is 4 cm. How long is the third side (in cm)?
  36. 36.The two interior opposite angles of a triangle are 68° and 66°. What is the exterior angle (in degrees)?
  37. 37.In a right-angled triangle, one of the other two angles is 41°. What is the third angle (in degrees)?
  38. 38.Can a triangle have sides of 18 cm, 10 cm and 10 cm? (a) Yes (b) No
  39. 39.In a right-angled triangle, one of the other two angles is 70°. What is the third angle (in degrees)?
  40. 40.In an isosceles triangle, the angle between the two equal sides is 96°. What is each of the other two angles (in degrees)?

Answer key

  1. 64
  2. 13
  3. 26
  4. 140
  5. 66
  6. 70
  7. 49
  8. 113
  9. 48
  10. 20
  11. 74
  12. 8
  13. 68
  14. 73
  15. 30
  16. 47
  17. 72
  18. No
  19. 76
  20. 36
  21. 11
  22. 136
  23. 13
  24. Yes
  25. 110
  26. 36
  27. 62
  28. Yes
  29. 87
  30. 63
  31. No
  32. 38
  33. 50
  34. 48
  35. 3
  36. 134
  37. 49
  38. Yes
  39. 20
  40. 42

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