← 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 26 · 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 66°. One of its two interior opposite angles is 40°. What is the other one (in degrees)?
  2. 2.In triangle ABC, angle A = 63° and angle B = 25°. What is angle C (in degrees)?
  3. 3.In a right-angled triangle, one of the other two angles is 44°. What is the third angle (in degrees)?
  4. 4.The longest side of a right-angled triangle is 39 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  5. 5.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  6. 6.The angles of a triangle are in the ratio 1 : 2 : 3. What is the smallest angle (in degrees)?
  7. 7.In a right-angled triangle, one of the other two angles is 10°. What is the third angle (in degrees)?
  8. 8.An exterior angle of a triangle is 100°. One of its two interior opposite angles is 64°. What is the other one (in degrees)?
  9. 9.The two interior opposite angles of a triangle are 48° and 20°. What is the exterior angle (in degrees)?
  10. 10.The longest side of a right-angled triangle is 20 cm and one of the other sides is 16 cm. How long is the third side (in cm)?
  11. 11.In an isosceles triangle, the angle between the two equal sides is 122°. What is each of the other two angles (in degrees)?
  12. 12.In an isosceles triangle, the angle between the two equal sides is 78°. What is each of the other two angles (in degrees)?
  13. 13.Can a triangle have sides of 17 cm, 12 cm and 3 cm? (a) No (b) Yes
  14. 14.In a right-angled triangle, one of the other two angles is 52°. What is the third angle (in degrees)?
  15. 15.An exterior angle of a triangle is 74°. One of its two interior opposite angles is 49°. What is the other one (in degrees)?
  16. 16.The angles of a triangle are in the ratio 1 : 2 : 2. What is the biggest angle (in degrees)?
  17. 17.An exterior angle of a triangle is 72°. One of its two interior opposite angles is 36°. What is the other one (in degrees)?
  18. 18.In triangle ABC, angle A = 50° and angle B = 78°. What is angle C (in degrees)?
  19. 19.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  20. 20.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  21. 21.In an isosceles triangle, the angle between the two equal sides is 44°. What is each of the other two angles (in degrees)?
  22. 22.In a right-angled triangle, one of the other two angles is 34°. What is the third angle (in degrees)?
  23. 23.Can a triangle have sides of 11 cm, 7 cm and 7 cm? (a) No (b) Yes
  24. 24.Can a triangle have sides of 7 cm, 5 cm and 14 cm? (a) No (b) Yes
  25. 25.Can a triangle have sides of 5 cm, 11 cm and 5 cm? (a) No (b) Yes
  26. 26.In triangle ABC, angle A = 39° and angle B = 35°. What is angle C (in degrees)?
  27. 27.Can a triangle have sides of 7 cm, 10 cm and 3 cm? (a) Yes (b) No
  28. 28.In a right-angled triangle, one of the other two angles is 49°. What is the third angle (in degrees)?
  29. 29.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)?
  30. 30.Can a triangle have sides of 4 cm, 3 cm and 5 cm? (a) No (b) Yes
  31. 31.Can a triangle have sides of 2 cm, 1 cm and 2 cm? (a) Yes (b) No
  32. 32.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  33. 33.In triangle ABC, angle A = 44° and angle B = 109°. What is angle C (in degrees)?
  34. 34.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)?
  35. 35.In an isosceles triangle, the two equal angles are 55° each. What is the third angle (in degrees)?
  36. 36.Can a triangle have sides of 7 cm, 9 cm and 17 cm? (a) No (b) Yes
  37. 37.The angles of a triangle are in the ratio 1 : 1 : 2. What is the smallest angle (in degrees)?
  38. 38.The two interior opposite angles of a triangle are 32° and 27°. What is the exterior angle (in degrees)?
  39. 39.The two interior opposite angles of a triangle are 68° and 21°. What is the exterior angle (in degrees)?
  40. 40.Can a triangle have sides of 10 cm, 10 cm and 7 cm? (a) Yes (b) No

Answer key

  1. 26
  2. 92
  3. 46
  4. 36
  5. 40
  6. 30
  7. 80
  8. 36
  9. 68
  10. 12
  11. 29
  12. 51
  13. No
  14. 38
  15. 25
  16. 72
  17. 36
  18. 52
  19. 17
  20. 100
  21. 68
  22. 56
  23. Yes
  24. No
  25. No
  26. 106
  27. No
  28. 41
  29. 20
  30. Yes
  31. Yes
  32. 25
  33. 27
  34. 8
  35. 70
  36. No
  37. 45
  38. 59
  39. 89
  40. Yes

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