← 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 51 · 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 3 : 5 : 7. What is the smallest angle (in degrees)?
  2. 2.In an isosceles triangle, the angle between the two equal sides is 86°. What is each of the other two angles (in degrees)?
  3. 3.In an isosceles triangle, the two equal angles are 27° each. What is the third angle (in degrees)?
  4. 4.Can a triangle have sides of 5 cm, 12 cm and 5 cm? (a) Yes (b) No
  5. 5.In an isosceles triangle, the angle between the two equal sides is 98°. What is each of the other two angles (in degrees)?
  6. 6.In triangle ABC, angle A = 57° and angle B = 83°. What is angle C (in degrees)?
  7. 7.Can a triangle have sides of 8 cm, 10 cm and 5 cm? (a) Yes (b) No
  8. 8.In a right-angled triangle, one of the other two angles is 57°. What is the third angle (in degrees)?
  9. 9.Can a triangle have sides of 2 cm, 12 cm and 12 cm? (a) No (b) Yes
  10. 10.In an isosceles triangle, the angle between the two equal sides is 34°. What is each of the other two angles (in degrees)?
  11. 11.The angles of a triangle are in the ratio 1 : 2 : 3. What is the smallest angle (in degrees)?
  12. 12.The two interior opposite angles of a triangle are 21° and 29°. What is the exterior angle (in degrees)?
  13. 13.An exterior angle of a triangle is 53°. One of its two interior opposite angles is 27°. What is the other one (in degrees)?
  14. 14.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  15. 15.In triangle ABC, angle A = 71° and angle B = 77°. What is angle C (in degrees)?
  16. 16.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  17. 17.In a right-angled triangle, one of the other two angles is 56°. What is the third angle (in degrees)?
  18. 18.In a right-angled triangle, one of the other two angles is 72°. What is the third angle (in degrees)?
  19. 19.Can a triangle have sides of 12 cm, 9 cm and 8 cm? (a) No (b) Yes
  20. 20.The longest side of a right-angled triangle is 13 cm and one of the other sides is 5 cm. How long is the third side (in cm)?
  21. 21.In triangle ABC, angle A = 61° and angle B = 72°. What is angle C (in degrees)?
  22. 22.The angles of a triangle are in the ratio 5 : 6 : 7. What is the smallest angle (in degrees)?
  23. 23.In triangle ABC, angle A = 32° and angle B = 90°. What is angle C (in degrees)?
  24. 24.In a right-angled triangle, one of the other two angles is 66°. What is the third angle (in degrees)?
  25. 25.In a right-angled triangle, one of the other two angles is 20°. What is the third angle (in degrees)?
  26. 26.In triangle ABC, angle A = 89° and angle B = 39°. What is angle C (in degrees)?
  27. 27.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)?
  28. 28.In triangle ABC, angle A = 47° and angle B = 97°. What is angle C (in degrees)?
  29. 29.In an isosceles triangle, the angle between the two equal sides is 122°. What is each of the other two angles (in degrees)?
  30. 30.Can a triangle have sides of 7 cm, 12 cm and 10 cm? (a) Yes (b) No
  31. 31.In triangle ABC, angle A = 45° and angle B = 28°. What is angle C (in degrees)?
  32. 32.In a right-angled triangle, one of the other two angles is 71°. What is the third angle (in degrees)?
  33. 33.In triangle ABC, angle A = 37° and angle B = 111°. What is angle C (in degrees)?
  34. 34.In triangle ABC, angle A = 40° and angle B = 48°. What is angle C (in degrees)?
  35. 35.In triangle ABC, angle A = 26° and angle B = 42°. What is angle C (in degrees)?
  36. 36.In a right-angled triangle, one of the other two angles is 34°. What is the third angle (in degrees)?
  37. 37.The longest side of a right-angled triangle is 15 cm and one of the other sides is 12 cm. How long is the third side (in cm)?
  38. 38.In an isosceles triangle, the two equal angles are 54° each. What is the third angle (in degrees)?
  39. 39.The angles of a triangle are in the ratio 3 : 5 : 7. What is the biggest angle (in degrees)?
  40. 40.Can a triangle have sides of 9 cm, 12 cm and 9 cm? (a) No (b) Yes

Answer key

  1. 36
  2. 47
  3. 126
  4. No
  5. 41
  6. 40
  7. Yes
  8. 33
  9. Yes
  10. 73
  11. 30
  12. 50
  13. 26
  14. 45
  15. 32
  16. 17
  17. 34
  18. 18
  19. Yes
  20. 12
  21. 47
  22. 50
  23. 58
  24. 24
  25. 70
  26. 52
  27. 8
  28. 36
  29. 29
  30. Yes
  31. 107
  32. 19
  33. 32
  34. 92
  35. 112
  36. 56
  37. 9
  38. 72
  39. 84
  40. Yes

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