← 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 356 · 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 an isosceles triangle, the angle between the two equal sides is 42°. What is each of the other two angles (in degrees)?
  2. 2.In triangle ABC, angle A = 34° and angle B = 33°. What is angle C (in degrees)?
  3. 3.In an isosceles triangle, the angle between the two equal sides is 56°. What is each of the other two angles (in degrees)?
  4. 4.The two interior opposite angles of a triangle are 25° and 70°. What is the exterior angle (in degrees)?
  5. 5.In a right-angled triangle, one of the other two angles is 34°. What is the third angle (in degrees)?
  6. 6.In an isosceles triangle, the angle between the two equal sides is 154°. What is each of the other two angles (in degrees)?
  7. 7.In a right-angled triangle, one of the other two angles is 65°. What is the third angle (in degrees)?
  8. 8.In triangle ABC, angle A = 37° and angle B = 28°. What is angle C (in degrees)?
  9. 9.In an isosceles triangle, the angle between the two equal sides is 134°. What is each of the other two angles (in degrees)?
  10. 10.An exterior angle of a triangle is 54°. One of its two interior opposite angles is 22°. What is the other one (in degrees)?
  11. 11.An exterior angle of a triangle is 61°. One of its two interior opposite angles is 41°. What is the other one (in degrees)?
  12. 12.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  13. 13.In triangle ABC, angle A = 46° and angle B = 23°. What is angle C (in degrees)?
  14. 14.The angles of a triangle are in the ratio 1 : 2 : 3. What is the biggest angle (in degrees)?
  15. 15.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)?
  16. 16.In triangle ABC, angle A = 75° and angle B = 25°. What is angle C (in degrees)?
  17. 17.In a right-angled triangle, one of the other two angles is 16°. What is the third angle (in degrees)?
  18. 18.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  19. 19.Can a triangle have sides of 9 cm, 4 cm and 9 cm? (a) Yes (b) No
  20. 20.In an isosceles triangle, the two equal angles are 36° each. What is the third angle (in degrees)?
  21. 21.The two shorter sides of a right-angled triangle are 12 cm and 5 cm. How long is the longest side (in cm)?
  22. 22.In a right-angled triangle, one of the other two angles is 15°. What is the third angle (in degrees)?
  23. 23.The longest side of a right-angled triangle is 17 cm and one of the other sides is 8 cm. How long is the third side (in cm)?
  24. 24.Can a triangle have sides of 18 cm, 5 cm and 9 cm? (a) Yes (b) No
  25. 25.In triangle ABC, angle A = 95° and angle B = 43°. What is angle C (in degrees)?
  26. 26.In a right-angled triangle, one of the other two angles is 71°. What is the third angle (in degrees)?
  27. 27.In triangle ABC, angle A = 33° and angle B = 30°. What is angle C (in degrees)?
  28. 28.In triangle ABC, angle A = 54° and angle B = 80°. What is angle C (in degrees)?
  29. 29.In an isosceles triangle, the two equal angles are 52° each. What is the third angle (in degrees)?
  30. 30.The longest side of a right-angled triangle is 13 cm and one of the other sides is 12 cm. How long is the third side (in cm)?
  31. 31.The two interior opposite angles of a triangle are 65° and 76°. What is the exterior angle (in degrees)?
  32. 32.In a right-angled triangle, one of the other two angles is 33°. What is the third angle (in degrees)?
  33. 33.In a right-angled triangle, one of the other two angles is 64°. What is the third angle (in degrees)?
  34. 34.Can a triangle have sides of 10 cm, 23 cm and 8 cm? (a) Yes (b) No
  35. 35.The two shorter sides of a right-angled triangle are 3 cm and 4 cm. How long is the longest side (in cm)?
  36. 36.The angles of a triangle are in the ratio 2 : 2 : 5. What is the smallest angle (in degrees)?
  37. 37.The two interior opposite angles of a triangle are 56° and 66°. What is the exterior angle (in degrees)?
  38. 38.The two interior opposite angles of a triangle are 22° and 68°. What is the exterior angle (in degrees)?
  39. 39.In triangle ABC, angle A = 71° and angle B = 80°. What is angle C (in degrees)?
  40. 40.In an isosceles triangle, the two equal angles are 56° each. What is the third angle (in degrees)?

Answer key

  1. 69
  2. 113
  3. 62
  4. 95
  5. 56
  6. 13
  7. 25
  8. 115
  9. 23
  10. 32
  11. 20
  12. 90
  13. 111
  14. 90
  15. 8
  16. 80
  17. 74
  18. 80
  19. Yes
  20. 108
  21. 13
  22. 75
  23. 15
  24. No
  25. 42
  26. 19
  27. 117
  28. 46
  29. 76
  30. 5
  31. 141
  32. 57
  33. 26
  34. No
  35. 5
  36. 40
  37. 122
  38. 90
  39. 29
  40. 68

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