← 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 513 · 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 154°. What is each of the other two angles (in degrees)?
  2. 2.The two interior opposite angles of a triangle are 51° and 35°. What is the exterior angle (in degrees)?
  3. 3.The two interior opposite angles of a triangle are 63° and 75°. What is the exterior angle (in degrees)?
  4. 4.In a right-angled triangle, one of the other two angles is 21°. What is the third angle (in degrees)?
  5. 5.In triangle ABC, angle A = 33° and angle B = 46°. What is angle C (in degrees)?
  6. 6.In an isosceles triangle, the angle between the two equal sides is 42°. What is each of the other two angles (in degrees)?
  7. 7.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)?
  8. 8.An exterior angle of a triangle is 73°. One of its two interior opposite angles is 27°. What is the other one (in degrees)?
  9. 9.An exterior angle of a triangle is 55°. One of its two interior opposite angles is 20°. What is the other one (in degrees)?
  10. 10.In triangle ABC, angle A = 79° and angle B = 76°. What is angle C (in degrees)?
  11. 11.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)?
  12. 12.The two shorter sides of a right-angled triangle are 24 cm and 18 cm. How long is the longest side (in cm)?
  13. 13.In an isosceles triangle, the angle between the two equal sides is 78°. What is each of the other two angles (in degrees)?
  14. 14.In a right-angled triangle, one of the other two angles is 52°. What is the third angle (in degrees)?
  15. 15.An exterior angle of a triangle is 56°. One of its two interior opposite angles is 25°. What is the other one (in degrees)?
  16. 16.In an isosceles triangle, the two equal angles are 81° each. What is the third angle (in degrees)?
  17. 17.In triangle ABC, angle A = 71° and angle B = 31°. What is angle C (in degrees)?
  18. 18.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  19. 19.The angles of a triangle are in the ratio 2 : 2 : 5. What is the smallest angle (in degrees)?
  20. 20.In triangle ABC, angle A = 44° and angle B = 53°. What is angle C (in degrees)?
  21. 21.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  22. 22.In a right-angled triangle, one of the other two angles is 70°. What is the third angle (in degrees)?
  23. 23.An exterior angle of a triangle is 94°. One of its two interior opposite angles is 26°. What is the other one (in degrees)?
  24. 24.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  25. 25.In triangle ABC, angle A = 33° and angle B = 122°. What is angle C (in degrees)?
  26. 26.In a right-angled triangle, one of the other two angles is 61°. What is the third angle (in degrees)?
  27. 27.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  28. 28.In a right-angled triangle, one of the other two angles is 48°. What is the third angle (in degrees)?
  29. 29.In a right-angled triangle, one of the other two angles is 67°. What is the third angle (in degrees)?
  30. 30.The two interior opposite angles of a triangle are 39° and 64°. What is the exterior angle (in degrees)?
  31. 31.Can a triangle have sides of 12 cm, 9 cm and 4 cm? (a) No (b) Yes
  32. 32.In a right-angled triangle, one of the other two angles is 27°. What is the third angle (in degrees)?
  33. 33.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  34. 34.The angles of a triangle are in the ratio 1 : 1 : 2. What is the smallest angle (in degrees)?
  35. 35.Can a triangle have sides of 22 cm, 10 cm and 9 cm? (a) Yes (b) No
  36. 36.The two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  37. 37.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  38. 38.The two interior opposite angles of a triangle are 37° and 28°. What is the exterior angle (in degrees)?
  39. 39.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  40. 40.In triangle ABC, angle A = 22° and angle B = 88°. What is angle C (in degrees)?

Answer key

  1. 13
  2. 86
  3. 138
  4. 69
  5. 101
  6. 69
  7. 24
  8. 46
  9. 35
  10. 25
  11. 15
  12. 30
  13. 51
  14. 38
  15. 31
  16. 18
  17. 78
  18. 17
  19. 40
  20. 83
  21. 72
  22. 20
  23. 68
  24. 120
  25. 25
  26. 29
  27. 20
  28. 42
  29. 23
  30. 103
  31. Yes
  32. 63
  33. 90
  34. 45
  35. No
  36. 39
  37. 80
  38. 65
  39. 75
  40. 70

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