← 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 457 · 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 28°. What is the third angle (in degrees)?
  2. 2.In a right-angled triangle, one of the other two angles is 48°. What is the third angle (in degrees)?
  3. 3.The two shorter sides of a right-angled triangle are 8 cm and 6 cm. How long is the longest side (in cm)?
  4. 4.The two interior opposite angles of a triangle are 29° and 38°. What is the exterior angle (in degrees)?
  5. 5.Can a triangle have sides of 11 cm, 7 cm and 8 cm? (a) No (b) Yes
  6. 6.In a right-angled triangle, one of the other two angles is 65°. What is the third angle (in degrees)?
  7. 7.Can a triangle have sides of 4 cm, 10 cm and 11 cm? (a) No (b) Yes
  8. 8.The longest side of a right-angled triangle is 5 cm and one of the other sides is 3 cm. How long is the third side (in cm)?
  9. 9.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  10. 10.Can a triangle have sides of 9 cm, 10 cm and 3 cm? (a) No (b) Yes
  11. 11.The two interior opposite angles of a triangle are 46° and 47°. What is the exterior angle (in degrees)?
  12. 12.The angles of a triangle are in the ratio 2 : 7 : 9. What is the biggest angle (in degrees)?
  13. 13.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  14. 14.In a right-angled triangle, one of the other two angles is 50°. What is the third angle (in degrees)?
  15. 15.The angles of a triangle are in the ratio 1 : 2 : 2. What is the biggest angle (in degrees)?
  16. 16.The angles of a triangle are in the ratio 2 : 3 : 4. What is the biggest angle (in degrees)?
  17. 17.In an isosceles triangle, the two equal angles are 23° each. What is the third angle (in degrees)?
  18. 18.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)?
  19. 19.The two interior opposite angles of a triangle are 27° and 58°. What is the exterior angle (in degrees)?
  20. 20.An exterior angle of a triangle is 98°. One of its two interior opposite angles is 35°. What is the other one (in degrees)?
  21. 21.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  22. 22.Can a triangle have sides of 16 cm, 11 cm and 3 cm? (a) No (b) Yes
  23. 23.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  24. 24.In triangle ABC, angle A = 90° and angle B = 69°. What is angle C (in degrees)?
  25. 25.In triangle ABC, angle A = 79° and angle B = 63°. What is angle C (in degrees)?
  26. 26.An exterior angle of a triangle is 140°. One of its two interior opposite angles is 76°. What is the other one (in degrees)?
  27. 27.In triangle ABC, angle A = 52° and angle B = 20°. What is angle C (in degrees)?
  28. 28.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)?
  29. 29.The two interior opposite angles of a triangle are 72° and 80°. What is the exterior angle (in degrees)?
  30. 30.In triangle ABC, angle A = 33° and angle B = 78°. What is angle C (in degrees)?
  31. 31.In triangle ABC, angle A = 65° and angle B = 28°. What is angle C (in degrees)?
  32. 32.The two shorter sides of a right-angled triangle are 20 cm and 15 cm. How long is the longest side (in cm)?
  33. 33.In triangle ABC, angle A = 93° and angle B = 39°. What is angle C (in degrees)?
  34. 34.The longest side of a right-angled triangle is 39 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  35. 35.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  36. 36.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  37. 37.In triangle ABC, angle A = 62° and angle B = 46°. What is angle C (in degrees)?
  38. 38.In an isosceles triangle, the angle between the two equal sides is 108°. What is each of the other two angles (in degrees)?
  39. 39.In triangle ABC, angle A = 55° and angle B = 36°. What is angle C (in degrees)?
  40. 40.In triangle ABC, angle A = 31° and angle B = 49°. What is angle C (in degrees)?

Answer key

  1. 62
  2. 42
  3. 10
  4. 67
  5. Yes
  6. 25
  7. Yes
  8. 4
  9. 25
  10. Yes
  11. 93
  12. 90
  13. 90
  14. 40
  15. 72
  16. 80
  17. 134
  18. 15
  19. 85
  20. 63
  21. 90
  22. No
  23. 20
  24. 21
  25. 38
  26. 64
  27. 108
  28. 7
  29. 152
  30. 69
  31. 87
  32. 25
  33. 48
  34. 36
  35. 17
  36. 75
  37. 72
  38. 36
  39. 89
  40. 100

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