← 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 86 · 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 angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  2. 2.In triangle ABC, angle A = 55° and angle B = 75°. What is angle C (in degrees)?
  3. 3.In a right-angled triangle, one of the other two angles is 19°. What is the third angle (in degrees)?
  4. 4.An exterior angle of a triangle is 76°. One of its two interior opposite angles is 50°. What is the other one (in degrees)?
  5. 5.In a right-angled triangle, one of the other two angles is 70°. What is the third angle (in degrees)?
  6. 6.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (in degrees)?
  7. 7.Can a triangle have sides of 12 cm, 3 cm and 14 cm? (a) No (b) Yes
  8. 8.The longest side of a right-angled triangle is 10 cm and one of the other sides is 6 cm. How long is the third side (in cm)?
  9. 9.In an isosceles triangle, the angle between the two equal sides is 160°. What is each of the other two angles (in degrees)?
  10. 10.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  11. 11.In a right-angled triangle, one of the other two angles is 46°. What is the third angle (in degrees)?
  12. 12.In triangle ABC, angle A = 36° and angle B = 47°. What is angle C (in degrees)?
  13. 13.In triangle ABC, angle A = 43° and angle B = 96°. What is angle C (in degrees)?
  14. 14.The two interior opposite angles of a triangle are 37° and 30°. What is the exterior angle (in degrees)?
  15. 15.Can a triangle have sides of 8 cm, 8 cm and 6 cm? (a) Yes (b) No
  16. 16.In an isosceles triangle, the angle between the two equal sides is 126°. What is each of the other two angles (in degrees)?
  17. 17.In triangle ABC, angle A = 95° and angle B = 58°. What is angle C (in degrees)?
  18. 18.The angles of a triangle are in the ratio 3 : 4 : 5. What is the smallest angle (in degrees)?
  19. 19.In an isosceles triangle, the angle between the two equal sides is 84°. What is each of the other two angles (in degrees)?
  20. 20.In triangle ABC, angle A = 83° and angle B = 34°. What is angle C (in degrees)?
  21. 21.The angles of a triangle are in the ratio 2 : 3 : 4. What is the smallest angle (in degrees)?
  22. 22.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)?
  23. 23.In an isosceles triangle, the angle between the two equal sides is 48°. What is each of the other two angles (in degrees)?
  24. 24.An exterior angle of a triangle is 106°. One of its two interior opposite angles is 77°. What is the other one (in degrees)?
  25. 25.In triangle ABC, angle A = 26° and angle B = 129°. What is angle C (in degrees)?
  26. 26.Can a triangle have sides of 7 cm, 17 cm and 7 cm? (a) Yes (b) No
  27. 27.In an isosceles triangle, the angle between the two equal sides is 70°. What is each of the other two angles (in degrees)?
  28. 28.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)?
  29. 29.In triangle ABC, angle A = 89° and angle B = 26°. What is angle C (in degrees)?
  30. 30.In a right-angled triangle, one of the other two angles is 40°. What is the third angle (in degrees)?
  31. 31.In a right-angled triangle, one of the other two angles is 79°. What is the third angle (in degrees)?
  32. 32.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  33. 33.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  34. 34.The angles of a triangle are in the ratio 2 : 3 : 5. What is the smallest angle (in degrees)?
  35. 35.In a right-angled triangle, one of the other two angles is 54°. What is the third angle (in degrees)?
  36. 36.In an isosceles triangle, the angle between the two equal sides is 36°. What is each of the other two angles (in degrees)?
  37. 37.In triangle ABC, angle A = 59° and angle B = 77°. What is angle C (in degrees)?
  38. 38.In triangle ABC, angle A = 95° and angle B = 23°. What is angle C (in degrees)?
  39. 39.An exterior angle of a triangle is 99°. One of its two interior opposite angles is 24°. What is the other one (in degrees)?
  40. 40.The two interior opposite angles of a triangle are 76° and 56°. What is the exterior angle (in degrees)?

Answer key

  1. 18
  2. 50
  3. 71
  4. 26
  5. 20
  6. 48
  7. Yes
  8. 8
  9. 10
  10. 100
  11. 44
  12. 97
  13. 41
  14. 67
  15. Yes
  16. 27
  17. 27
  18. 45
  19. 48
  20. 63
  21. 40
  22. 8
  23. 66
  24. 29
  25. 25
  26. No
  27. 55
  28. 24
  29. 65
  30. 50
  31. 11
  32. 17
  33. 90
  34. 36
  35. 36
  36. 72
  37. 44
  38. 62
  39. 75
  40. 132

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