← 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 109 · 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.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  2. 2.An exterior angle of a triangle is 88°. One of its two interior opposite angles is 44°. What is the other one (in degrees)?
  3. 3.Can a triangle have sides of 5 cm, 7 cm and 3 cm? (a) No (b) Yes
  4. 4.The angles of a triangle are in the ratio 2 : 7 : 9. What is the biggest angle (in degrees)?
  5. 5.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  6. 6.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)?
  7. 7.The two shorter sides of a right-angled triangle are 24 cm and 10 cm. How long is the longest side (in cm)?
  8. 8.The angles of a triangle are in the ratio 1 : 2 : 2. What is the smallest angle (in degrees)?
  9. 9.In an isosceles triangle, the two equal angles are 71° each. What is the third angle (in degrees)?
  10. 10.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (in degrees)?
  11. 11.Can a triangle have sides of 12 cm, 16 cm and 4 cm? (a) No (b) Yes
  12. 12.The two shorter sides of a right-angled triangle are 3 cm and 4 cm. How long is the longest side (in cm)?
  13. 13.Can a triangle have sides of 15 cm, 12 cm and 8 cm? (a) Yes (b) No
  14. 14.Can a triangle have sides of 8 cm, 17 cm and 10 cm? (a) No (b) Yes
  15. 15.Can a triangle have sides of 7 cm, 21 cm and 10 cm? (a) Yes (b) No
  16. 16.The two shorter sides of a right-angled triangle are 18 cm and 24 cm. How long is the longest side (in cm)?
  17. 17.In triangle ABC, angle A = 45° and angle B = 80°. What is angle C (in degrees)?
  18. 18.In an isosceles triangle, the two equal angles are 40° each. What is the third angle (in degrees)?
  19. 19.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  20. 20.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  21. 21.In triangle ABC, angle A = 67° and angle B = 57°. What is angle C (in degrees)?
  22. 22.Can a triangle have sides of 9 cm, 9 cm and 6 cm? (a) No (b) Yes
  23. 23.Can a triangle have sides of 7 cm, 4 cm and 8 cm? (a) Yes (b) No
  24. 24.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)?
  25. 25.In an isosceles triangle, the angle between the two equal sides is 56°. What is each of the other two angles (in degrees)?
  26. 26.The longest side of a right-angled triangle is 10 cm and one of the other sides is 8 cm. How long is the third side (in cm)?
  27. 27.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  28. 28.The two interior opposite angles of a triangle are 57° and 68°. What is the exterior angle (in degrees)?
  29. 29.Can a triangle have sides of 7 cm, 6 cm and 6 cm? (a) Yes (b) No
  30. 30.In triangle ABC, angle A = 36° and angle B = 84°. What is angle C (in degrees)?
  31. 31.Can a triangle have sides of 7 cm, 7 cm and 15 cm? (a) Yes (b) No
  32. 32.The angles of a triangle are in the ratio 1 : 2 : 3. What is the biggest angle (in degrees)?
  33. 33.In triangle ABC, angle A = 57° and angle B = 52°. What is angle C (in degrees)?
  34. 34.In triangle ABC, angle A = 94° and angle B = 29°. What is angle C (in degrees)?
  35. 35.In a right-angled triangle, one of the other two angles is 52°. What is the third angle (in degrees)?
  36. 36.In an isosceles triangle, the angle between the two equal sides is 96°. What is each of the other two angles (in degrees)?
  37. 37.The two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  38. 38.An exterior angle of a triangle is 59°. One of its two interior opposite angles is 20°. What is the other one (in degrees)?
  39. 39.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  40. 40.In triangle ABC, angle A = 33° and angle B = 95°. What is angle C (in degrees)?

Answer key

  1. 90
  2. 44
  3. Yes
  4. 90
  5. 80
  6. 8
  7. 26
  8. 36
  9. 38
  10. 72
  11. No
  12. 5
  13. Yes
  14. Yes
  15. No
  16. 30
  17. 55
  18. 100
  19. 120
  20. 100
  21. 56
  22. Yes
  23. Yes
  24. 24
  25. 62
  26. 6
  27. 20
  28. 125
  29. Yes
  30. 60
  31. No
  32. 90
  33. 71
  34. 57
  35. 38
  36. 42
  37. 39
  38. 39
  39. 17
  40. 52

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