← 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 623 · 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 27°. What is the third angle (in degrees)?
  2. 2.In an isosceles triangle, the angle between the two equal sides is 60°. What is each of the other two angles (in degrees)?
  3. 3.In triangle ABC, angle A = 52° and angle B = 101°. What is angle C (in degrees)?
  4. 4.An exterior angle of a triangle is 133°. One of its two interior opposite angles is 65°. What is the other one (in degrees)?
  5. 5.Can a triangle have sides of 7 cm, 6 cm and 2 cm? (a) No (b) Yes
  6. 6.Can a triangle have sides of 5 cm, 6 cm and 3 cm? (a) Yes (b) No
  7. 7.In triangle ABC, angle A = 44° and angle B = 96°. What is angle C (in degrees)?
  8. 8.The two interior opposite angles of a triangle are 34° and 64°. What is the exterior angle (in degrees)?
  9. 9.An exterior angle of a triangle is 71°. One of its two interior opposite angles is 40°. What is the other one (in degrees)?
  10. 10.In a right-angled triangle, one of the other two angles is 25°. What is the third angle (in degrees)?
  11. 11.In triangle ABC, angle A = 76° and angle B = 48°. What is angle C (in degrees)?
  12. 12.Can a triangle have sides of 24 cm, 10 cm and 10 cm? (a) Yes (b) No
  13. 13.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  14. 14.In a right-angled triangle, one of the other two angles is 14°. What is the third angle (in degrees)?
  15. 15.In a right-angled triangle, one of the other two angles is 49°. What is the third angle (in degrees)?
  16. 16.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  17. 17.In an isosceles triangle, the two equal angles are 59° each. What is the third angle (in degrees)?
  18. 18.The two interior opposite angles of a triangle are 23° and 72°. What is the exterior angle (in degrees)?
  19. 19.Can a triangle have sides of 10 cm, 7 cm and 8 cm? (a) No (b) Yes
  20. 20.In an isosceles triangle, the angle between the two equal sides is 68°. What is each of the other two angles (in degrees)?
  21. 21.In an isosceles triangle, the two equal angles are 49° each. What is the third angle (in degrees)?
  22. 22.In an isosceles triangle, the angle between the two equal sides is 70°. What is each of the other two angles (in degrees)?
  23. 23.In an isosceles triangle, the two equal angles are 36° each. What is the third angle (in degrees)?
  24. 24.An exterior angle of a triangle is 109°. One of its two interior opposite angles is 57°. What is the other one (in degrees)?
  25. 25.An exterior angle of a triangle is 74°. One of its two interior opposite angles is 51°. What is the other one (in degrees)?
  26. 26.In a right-angled triangle, one of the other two angles is 70°. What is the third angle (in degrees)?
  27. 27.In a right-angled triangle, one of the other two angles is 47°. What is the third angle (in degrees)?
  28. 28.An exterior angle of a triangle is 94°. One of its two interior opposite angles is 39°. What is the other one (in degrees)?
  29. 29.The two shorter sides of a right-angled triangle are 15 cm and 20 cm. How long is the longest side (in cm)?
  30. 30.The two shorter sides of a right-angled triangle are 10 cm and 24 cm. How long is the longest side (in cm)?
  31. 31.An exterior angle of a triangle is 90°. One of its two interior opposite angles is 56°. What is the other one (in degrees)?
  32. 32.The two interior opposite angles of a triangle are 25° and 62°. What is the exterior angle (in degrees)?
  33. 33.The two interior opposite angles of a triangle are 69° and 79°. What is the exterior angle (in degrees)?
  34. 34.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  35. 35.In triangle ABC, angle A = 86° and angle B = 32°. What is angle C (in degrees)?
  36. 36.Can a triangle have sides of 3 cm, 11 cm and 13 cm? (a) No (b) Yes
  37. 37.In triangle ABC, angle A = 27° and angle B = 83°. What is angle C (in degrees)?
  38. 38.Can a triangle have sides of 15 cm, 9 cm and 12 cm? (a) Yes (b) No
  39. 39.The two interior opposite angles of a triangle are 44° and 59°. What is the exterior angle (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 31°. What is the third angle (in degrees)?

Answer key

  1. 63
  2. 60
  3. 27
  4. 68
  5. Yes
  6. Yes
  7. 40
  8. 98
  9. 31
  10. 65
  11. 56
  12. No
  13. 72
  14. 76
  15. 41
  16. 25
  17. 62
  18. 95
  19. Yes
  20. 56
  21. 82
  22. 55
  23. 108
  24. 52
  25. 23
  26. 20
  27. 43
  28. 55
  29. 25
  30. 26
  31. 34
  32. 87
  33. 148
  34. 90
  35. 62
  36. Yes
  37. 70
  38. Yes
  39. 103
  40. 59

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