← 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 583 · 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 two interior opposite angles of a triangle are 34° and 65°. What is the exterior angle (in degrees)?
  2. 2.In a right-angled triangle, one of the other two angles is 25°. What is the third angle (in degrees)?
  3. 3.In an isosceles triangle, the two equal angles are 23° each. What is the third angle (in degrees)?
  4. 4.An exterior angle of a triangle is 61°. One of its two interior opposite angles is 30°. What is the other one (in degrees)?
  5. 5.The longest side of a right-angled triangle is 20 cm and one of the other sides is 12 cm. How long is the third side (in cm)?
  6. 6.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  7. 7.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  8. 8.The two interior opposite angles of a triangle are 25° and 25°. What is the exterior angle (in degrees)?
  9. 9.The two interior opposite angles of a triangle are 75° and 34°. What is the exterior angle (in degrees)?
  10. 10.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  11. 11.An exterior angle of a triangle is 71°. One of its two interior opposite angles is 48°. What is the other one (in degrees)?
  12. 12.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)?
  13. 13.The two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  14. 14.Can a triangle have sides of 8 cm, 20 cm and 12 cm? (a) Yes (b) No
  15. 15.Can a triangle have sides of 4 cm, 6 cm and 5 cm? (a) Yes (b) No
  16. 16.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  17. 17.In triangle ABC, angle A = 54° and angle B = 77°. What is angle C (in degrees)?
  18. 18.The two interior opposite angles of a triangle are 23° and 25°. What is the exterior angle (in degrees)?
  19. 19.In triangle ABC, angle A = 56° and angle B = 77°. What is angle C (in degrees)?
  20. 20.In triangle ABC, angle A = 52° and angle B = 74°. What is angle C (in degrees)?
  21. 21.In a right-angled triangle, one of the other two angles is 42°. What is the third angle (in degrees)?
  22. 22.An exterior angle of a triangle is 90°. One of its two interior opposite angles is 26°. What is the other one (in degrees)?
  23. 23.Can a triangle have sides of 9 cm, 7 cm and 21 cm? (a) Yes (b) No
  24. 24.The two interior opposite angles of a triangle are 27° and 65°. What is the exterior angle (in degrees)?
  25. 25.Can a triangle have sides of 10 cm, 7 cm and 3 cm? (a) No (b) Yes
  26. 26.In an isosceles triangle, the angle between the two equal sides is 112°. What is each of the other two angles (in degrees)?
  27. 27.In triangle ABC, angle A = 50° and angle B = 42°. What is angle C (in degrees)?
  28. 28.In an isosceles triangle, the two equal angles are 81° each. What is the third angle (in degrees)?
  29. 29.In an isosceles triangle, the two equal angles are 67° each. What is the third angle (in degrees)?
  30. 30.In triangle ABC, angle A = 41° and angle B = 98°. What is angle C (in degrees)?
  31. 31.In triangle ABC, angle A = 22° and angle B = 125°. What is angle C (in degrees)?
  32. 32.An exterior angle of a triangle is 97°. One of its two interior opposite angles is 63°. What is the other one (in degrees)?
  33. 33.In a right-angled triangle, one of the other two angles is 76°. What is the third angle (in degrees)?
  34. 34.The longest side of a right-angled triangle is 25 cm and one of the other sides is 24 cm. How long is the third side (in cm)?
  35. 35.The two shorter sides of a right-angled triangle are 36 cm and 15 cm. How long is the longest side (in cm)?
  36. 36.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)?
  37. 37.In an isosceles triangle, the two equal angles are 31° each. What is the third angle (in degrees)?
  38. 38.In triangle ABC, angle A = 51° and angle B = 33°. What is angle C (in degrees)?
  39. 39.The two shorter sides of a right-angled triangle are 12 cm and 5 cm. How long is the longest side (in cm)?
  40. 40.Can a triangle have sides of 12 cm, 21 cm and 5 cm? (a) No (b) Yes

Answer key

  1. 99
  2. 65
  3. 134
  4. 31
  5. 16
  6. 25
  7. 90
  8. 50
  9. 109
  10. 75
  11. 23
  12. 5
  13. 39
  14. No
  15. Yes
  16. 90
  17. 49
  18. 48
  19. 47
  20. 54
  21. 48
  22. 64
  23. No
  24. 92
  25. No
  26. 34
  27. 88
  28. 18
  29. 46
  30. 41
  31. 33
  32. 34
  33. 14
  34. 7
  35. 39
  36. 8
  37. 118
  38. 96
  39. 13
  40. No

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