← 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 600 · 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 122°. What is each of the other two angles (in degrees)?
  2. 2.In triangle ABC, angle A = 78° and angle B = 65°. What is angle C (in degrees)?
  3. 3.An exterior angle of a triangle is 90°. One of its two interior opposite angles is 28°. What is the other one (in degrees)?
  4. 4.In triangle ABC, angle A = 21° and angle B = 103°. What is angle C (in degrees)?
  5. 5.In triangle ABC, angle A = 41° and angle B = 106°. What is angle C (in degrees)?
  6. 6.An exterior angle of a triangle is 73°. One of its two interior opposite angles is 31°. What is the other one (in degrees)?
  7. 7.The angles of a triangle are in the ratio 3 : 3 : 4. What is the smallest angle (in degrees)?
  8. 8.In triangle ABC, angle A = 67° and angle B = 80°. What is angle C (in degrees)?
  9. 9.In an isosceles triangle, the two equal angles are 84° each. What is the third angle (in degrees)?
  10. 10.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  11. 11.In an isosceles triangle, the two equal angles are 75° each. What is the third angle (in degrees)?
  12. 12.The longest side of a right-angled triangle is 25 cm and one of the other sides is 7 cm. How long is the third side (in cm)?
  13. 13.The two interior opposite angles of a triangle are 30° and 29°. What is the exterior angle (in degrees)?
  14. 14.In triangle ABC, angle A = 42° and angle B = 92°. What is angle C (in degrees)?
  15. 15.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)?
  16. 16.An exterior angle of a triangle is 148°. One of its two interior opposite angles is 68°. What is the other one (in degrees)?
  17. 17.An exterior angle of a triangle is 46°. One of its two interior opposite angles is 24°. What is the other one (in degrees)?
  18. 18.The two interior opposite angles of a triangle are 25° and 72°. What is the exterior angle (in degrees)?
  19. 19.An exterior angle of a triangle is 76°. One of its two interior opposite angles is 53°. What is the other one (in degrees)?
  20. 20.In an isosceles triangle, the angle between the two equal sides is 20°. What is each of the other two angles (in degrees)?
  21. 21.The two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  22. 22.An exterior angle of a triangle is 72°. One of its two interior opposite angles is 30°. What is the other one (in degrees)?
  23. 23.The two interior opposite angles of a triangle are 69° and 21°. What is the exterior angle (in degrees)?
  24. 24.Can a triangle have sides of 3 cm, 3 cm and 10 cm? (a) No (b) Yes
  25. 25.An exterior angle of a triangle is 81°. One of its two interior opposite angles is 27°. What is the other one (in degrees)?
  26. 26.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)?
  27. 27.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  28. 28.In triangle ABC, angle A = 21° and angle B = 29°. What is angle C (in degrees)?
  29. 29.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)?
  30. 30.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  31. 31.In triangle ABC, angle A = 73° and angle B = 49°. What is angle C (in degrees)?
  32. 32.An exterior angle of a triangle is 85°. One of its two interior opposite angles is 28°. What is the other one (in degrees)?
  33. 33.Can a triangle have sides of 5 cm, 5 cm and 14 cm? (a) Yes (b) No
  34. 34.Can a triangle have sides of 10 cm, 22 cm and 8 cm? (a) Yes (b) No
  35. 35.An exterior angle of a triangle is 94°. One of its two interior opposite angles is 60°. What is the other one (in degrees)?
  36. 36.In a right-angled triangle, one of the other two angles is 60°. What is the third angle (in degrees)?
  37. 37.An exterior angle of a triangle is 69°. One of its two interior opposite angles is 33°. What is the other one (in degrees)?
  38. 38.Can a triangle have sides of 6 cm, 11 cm and 6 cm? (a) Yes (b) No
  39. 39.Can a triangle have sides of 8 cm, 8 cm and 17 cm? (a) No (b) Yes
  40. 40.In a right-angled triangle, one of the other two angles is 62°. What is the third angle (in degrees)?

Answer key

  1. 29
  2. 37
  3. 62
  4. 56
  5. 33
  6. 42
  7. 54
  8. 33
  9. 12
  10. 90
  11. 30
  12. 24
  13. 59
  14. 46
  15. 24
  16. 80
  17. 22
  18. 97
  19. 23
  20. 80
  21. 39
  22. 42
  23. 90
  24. No
  25. 54
  26. 15
  27. 17
  28. 130
  29. 12
  30. 40
  31. 58
  32. 57
  33. No
  34. No
  35. 34
  36. 30
  37. 36
  38. Yes
  39. No
  40. 28

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