← 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 753 · 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 longest side of a right-angled triangle is 15 cm and one of the other sides is 9 cm. How long is the third side (in cm)?
  2. 2.An exterior angle of a triangle is 97°. One of its two interior opposite angles is 60°. What is the other one (in degrees)?
  3. 3.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)?
  4. 4.Can a triangle have sides of 7 cm, 7 cm and 13 cm? (a) Yes (b) No
  5. 5.In triangle ABC, angle A = 94° and angle B = 32°. What is angle C (in degrees)?
  6. 6.In an isosceles triangle, the angle between the two equal sides is 108°. What is each of the other two angles (in degrees)?
  7. 7.In a right-angled triangle, one of the other two angles is 32°. What is the third angle (in degrees)?
  8. 8.Can a triangle have sides of 3 cm, 4 cm and 2 cm? (a) No (b) Yes
  9. 9.In an isosceles triangle, the two equal angles are 45° each. What is the third angle (in degrees)?
  10. 10.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)?
  11. 11.The two interior opposite angles of a triangle are 47° and 66°. What is the exterior angle (in degrees)?
  12. 12.The two interior opposite angles of a triangle are 69° and 43°. What is the exterior angle (in degrees)?
  13. 13.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  14. 14.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  15. 15.In an isosceles triangle, the two equal angles are 44° each. What is the third angle (in degrees)?
  16. 16.In an isosceles triangle, the two equal angles are 54° each. What is the third angle (in degrees)?
  17. 17.An exterior angle of a triangle is 59°. One of its two interior opposite angles is 32°. What is the other one (in degrees)?
  18. 18.Can a triangle have sides of 6 cm, 14 cm and 5 cm? (a) No (b) Yes
  19. 19.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  20. 20.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)?
  21. 21.In a right-angled triangle, one of the other two angles is 54°. What is the third angle (in degrees)?
  22. 22.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  23. 23.In a right-angled triangle, one of the other two angles is 68°. What is the third angle (in degrees)?
  24. 24.Can a triangle have sides of 8 cm, 6 cm and 10 cm? (a) Yes (b) No
  25. 25.The two shorter sides of a right-angled triangle are 12 cm and 5 cm. How long is the longest side (in cm)?
  26. 26.An exterior angle of a triangle is 99°. One of its two interior opposite angles is 26°. What is the other one (in degrees)?
  27. 27.An exterior angle of a triangle is 112°. One of its two interior opposite angles is 76°. What is the other one (in degrees)?
  28. 28.In a right-angled triangle, one of the other two angles is 59°. What is the third angle (in degrees)?
  29. 29.The two interior opposite angles of a triangle are 64° and 62°. What is the exterior angle (in degrees)?
  30. 30.In an isosceles triangle, the angle between the two equal sides is 24°. What is each of the other two angles (in degrees)?
  31. 31.In an isosceles triangle, the two equal angles are 36° each. What is the third angle (in degrees)?
  32. 32.In an isosceles triangle, the two equal angles are 27° each. What is the third angle (in degrees)?
  33. 33.Can a triangle have sides of 5 cm, 10 cm and 6 cm? (a) Yes (b) No
  34. 34.Can a triangle have sides of 10 cm, 14 cm and 2 cm? (a) Yes (b) No
  35. 35.In triangle ABC, angle A = 43° and angle B = 89°. What is angle C (in degrees)?
  36. 36.In an isosceles triangle, the two equal angles are 31° each. What is the third angle (in degrees)?
  37. 37.The two interior opposite angles of a triangle are 40° and 69°. What is the exterior angle (in degrees)?
  38. 38.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  39. 39.The two interior opposite angles of a triangle are 74° and 38°. What is the exterior angle (in degrees)?
  40. 40.In triangle ABC, angle A = 68° and angle B = 62°. What is angle C (in degrees)?

Answer key

  1. 12
  2. 37
  3. 8
  4. Yes
  5. 54
  6. 36
  7. 58
  8. Yes
  9. 90
  10. 15
  11. 113
  12. 112
  13. 17
  14. 17
  15. 92
  16. 72
  17. 27
  18. No
  19. 20
  20. 24
  21. 36
  22. 80
  23. 22
  24. Yes
  25. 13
  26. 73
  27. 36
  28. 31
  29. 126
  30. 78
  31. 108
  32. 126
  33. Yes
  34. No
  35. 48
  36. 118
  37. 109
  38. 45
  39. 112
  40. 50

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