← 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 350 · 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 a right-angled triangle, one of the other two angles is 14°. What is the third angle (in degrees)?
  2. 2.In a right-angled triangle, one of the other two angles is 15°. What is the third angle (in degrees)?
  3. 3.In triangle ABC, angle A = 68° and angle B = 90°. What is angle C (in degrees)?
  4. 4.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  5. 5.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)?
  6. 6.In triangle ABC, angle A = 75° and angle B = 74°. What is angle C (in degrees)?
  7. 7.In triangle ABC, angle A = 40° and angle B = 23°. What is angle C (in degrees)?
  8. 8.An exterior angle of a triangle is 76°. One of its two interior opposite angles is 48°. What is the other one (in degrees)?
  9. 9.In a right-angled triangle, one of the other two angles is 36°. What is the third angle (in degrees)?
  10. 10.Can a triangle have sides of 3 cm, 12 cm and 10 cm? (a) Yes (b) No
  11. 11.In an isosceles triangle, the angle between the two equal sides is 30°. What is each of the other two angles (in degrees)?
  12. 12.In an isosceles triangle, the two equal angles are 77° each. What is the third angle (in degrees)?
  13. 13.In triangle ABC, angle A = 96° and angle B = 50°. What is angle C (in degrees)?
  14. 14.The two shorter sides of a right-angled triangle are 24 cm and 7 cm. How long is the longest side (in cm)?
  15. 15.In triangle ABC, angle A = 26° and angle B = 50°. What is angle C (in degrees)?
  16. 16.Can a triangle have sides of 3 cm, 12 cm and 9 cm? (a) No (b) Yes
  17. 17.In a right-angled triangle, one of the other two angles is 77°. What is the third angle (in degrees)?
  18. 18.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  19. 19.In triangle ABC, angle A = 76° and angle B = 42°. What is angle C (in degrees)?
  20. 20.Can a triangle have sides of 21 cm, 10 cm and 10 cm? (a) No (b) Yes
  21. 21.In a right-angled triangle, one of the other two angles is 65°. What is the third angle (in degrees)?
  22. 22.An exterior angle of a triangle is 129°. One of its two interior opposite angles is 55°. What is the other one (in degrees)?
  23. 23.Can a triangle have sides of 10 cm, 8 cm and 20 cm? (a) Yes (b) No
  24. 24.Can a triangle have sides of 23 cm, 10 cm and 10 cm? (a) Yes (b) No
  25. 25.The two interior opposite angles of a triangle are 71° and 76°. What is the exterior angle (in degrees)?
  26. 26.In an isosceles triangle, the two equal angles are 78° each. What is the third angle (in degrees)?
  27. 27.The two interior opposite angles of a triangle are 32° and 40°. What is the exterior angle (in degrees)?
  28. 28.The two interior opposite angles of a triangle are 55° and 46°. What is the exterior angle (in degrees)?
  29. 29.In a right-angled triangle, one of the other two angles is 20°. What is the third angle (in degrees)?
  30. 30.An exterior angle of a triangle is 98°. One of its two interior opposite angles is 28°. What is the other one (in degrees)?
  31. 31.The angles of a triangle are in the ratio 1 : 2 : 6. What is the smallest angle (in degrees)?
  32. 32.An exterior angle of a triangle is 66°. One of its two interior opposite angles is 27°. What is the other one (in degrees)?
  33. 33.In a right-angled triangle, one of the other two angles is 48°. What is the third angle (in degrees)?
  34. 34.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  35. 35.An exterior angle of a triangle is 106°. One of its two interior opposite angles is 64°. What is the other one (in degrees)?
  36. 36.In triangle ABC, angle A = 63° and angle B = 45°. What is angle C (in degrees)?
  37. 37.The two interior opposite angles of a triangle are 28° and 59°. What is the exterior angle (in degrees)?
  38. 38.In an isosceles triangle, the angle between the two equal sides is 106°. What is each of the other two angles (in degrees)?
  39. 39.In a right-angled triangle, one of the other two angles is 44°. What is the third angle (in degrees)?
  40. 40.The two shorter sides of a right-angled triangle are 12 cm and 9 cm. How long is the longest side (in cm)?

Answer key

  1. 76
  2. 75
  3. 22
  4. 100
  5. 15
  6. 31
  7. 117
  8. 28
  9. 54
  10. Yes
  11. 75
  12. 26
  13. 34
  14. 25
  15. 104
  16. No
  17. 13
  18. 36
  19. 62
  20. No
  21. 25
  22. 74
  23. No
  24. No
  25. 147
  26. 24
  27. 72
  28. 101
  29. 70
  30. 70
  31. 20
  32. 39
  33. 42
  34. 72
  35. 42
  36. 72
  37. 87
  38. 37
  39. 46
  40. 15

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