← 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 136 · 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 140°. What is each of the other two angles (in degrees)?
  2. 2.The two interior opposite angles of a triangle are 64° and 37°. What is the exterior angle (in degrees)?
  3. 3.The two shorter sides of a right-angled triangle are 5 cm and 12 cm. How long is the longest side (in cm)?
  4. 4.The two shorter sides of a right-angled triangle are 15 cm and 20 cm. How long is the longest side (in cm)?
  5. 5.In triangle ABC, angle A = 22° and angle B = 95°. What is angle C (in degrees)?
  6. 6.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)?
  7. 7.In triangle ABC, angle A = 32° and angle B = 86°. What is angle C (in degrees)?
  8. 8.An exterior angle of a triangle is 93°. One of its two interior opposite angles is 39°. What is the other one (in degrees)?
  9. 9.The two interior opposite angles of a triangle are 43° and 68°. What is the exterior angle (in degrees)?
  10. 10.An exterior angle of a triangle is 49°. One of its two interior opposite angles is 28°. What is the other one (in degrees)?
  11. 11.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  12. 12.Can a triangle have sides of 15 cm, 8 cm and 5 cm? (a) No (b) Yes
  13. 13.In an isosceles triangle, the two equal angles are 80° each. What is the third angle (in degrees)?
  14. 14.In triangle ABC, angle A = 100° and angle B = 21°. What is angle C (in degrees)?
  15. 15.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  16. 16.Can a triangle have sides of 8 cm, 21 cm and 8 cm? (a) No (b) Yes
  17. 17.Can a triangle have sides of 8 cm, 10 cm and 17 cm? (a) Yes (b) No
  18. 18.Can a triangle have sides of 7 cm, 9 cm and 8 cm? (a) No (b) Yes
  19. 19.An exterior angle of a triangle is 93°. One of its two interior opposite angles is 53°. What is the other one (in degrees)?
  20. 20.Can a triangle have sides of 3 cm, 4 cm and 9 cm? (a) Yes (b) No
  21. 21.The two interior opposite angles of a triangle are 42° and 67°. What is the exterior angle (in degrees)?
  22. 22.In triangle ABC, angle A = 65° and angle B = 37°. What is angle C (in degrees)?
  23. 23.In triangle ABC, angle A = 83° and angle B = 20°. What is angle C (in degrees)?
  24. 24.An exterior angle of a triangle is 44°. One of its two interior opposite angles is 23°. What is the other one (in degrees)?
  25. 25.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (in degrees)?
  26. 26.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)?
  27. 27.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)?
  28. 28.An exterior angle of a triangle is 56°. One of its two interior opposite angles is 29°. What is the other one (in degrees)?
  29. 29.In an isosceles triangle, the two equal angles are 64° each. What is the third angle (in degrees)?
  30. 30.The two interior opposite angles of a triangle are 29° and 45°. What is the exterior angle (in degrees)?
  31. 31.An exterior angle of a triangle is 106°. One of its two interior opposite angles is 35°. What is the other one (in degrees)?
  32. 32.The angles of a triangle are in the ratio 4 : 5 : 6. What is the smallest angle (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.In an isosceles triangle, the two equal angles are 33° each. What is the third angle (in degrees)?
  35. 35.In an isosceles triangle, the angle between the two equal sides is 142°. What is each of the other two angles (in degrees)?
  36. 36.Can a triangle have sides of 7 cm, 17 cm and 7 cm? (a) Yes (b) No
  37. 37.In an isosceles triangle, the angle between the two equal sides is 58°. What is each of the other two angles (in degrees)?
  38. 38.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  39. 39.In an isosceles triangle, the two equal angles are 59° each. What is the third angle (in degrees)?
  40. 40.The angles of a triangle are in the ratio 5 : 6 : 7. What is the biggest angle (in degrees)?

Answer key

  1. 20
  2. 101
  3. 13
  4. 25
  5. 63
  6. 7
  7. 62
  8. 54
  9. 111
  10. 21
  11. 72
  12. No
  13. 20
  14. 59
  15. 20
  16. No
  17. Yes
  18. Yes
  19. 40
  20. No
  21. 109
  22. 78
  23. 77
  24. 21
  25. 72
  26. 12
  27. 15
  28. 27
  29. 52
  30. 74
  31. 71
  32. 48
  33. 42
  34. 114
  35. 19
  36. No
  37. 61
  38. 18
  39. 62
  40. 70

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