← 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 805 · 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 11°. What is the third angle (in degrees)?
  2. 2.In an isosceles triangle, the angle between the two equal sides is 42°. What is each of the other two angles (in degrees)?
  3. 3.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  4. 4.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  5. 5.Can a triangle have sides of 5 cm, 3 cm and 3 cm? (a) Yes (b) No
  6. 6.Can a triangle have sides of 10 cm, 7 cm and 11 cm? (a) No (b) Yes
  7. 7.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)?
  8. 8.In triangle ABC, angle A = 21° and angle B = 99°. What is angle C (in degrees)?
  9. 9.The angles of a triangle are in the ratio 3 : 3 : 4. What is the smallest angle (in degrees)?
  10. 10.In an isosceles triangle, the angle between the two equal sides is 96°. What is each of the other two angles (in degrees)?
  11. 11.The two interior opposite angles of a triangle are 44° and 68°. What is the exterior angle (in degrees)?
  12. 12.The two interior opposite angles of a triangle are 47° and 74°. What is the exterior angle (in degrees)?
  13. 13.The angles of a triangle are in the ratio 1 : 2 : 2. What is the smallest angle (in degrees)?
  14. 14.The angles of a triangle are in the ratio 1 : 2 : 6. What is the biggest angle (in degrees)?
  15. 15.An exterior angle of a triangle is 92°. One of its two interior opposite angles is 28°. What is the other one (in degrees)?
  16. 16.Can a triangle have sides of 10 cm, 22 cm and 10 cm? (a) Yes (b) No
  17. 17.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  18. 18.The two shorter sides of a right-angled triangle are 24 cm and 10 cm. How long is the longest side (in cm)?
  19. 19.The two interior opposite angles of a triangle are 73° and 54°. What is the exterior angle (in degrees)?
  20. 20.In triangle ABC, angle A = 50° and angle B = 73°. What is angle C (in degrees)?
  21. 21.Can a triangle have sides of 7 cm, 12 cm and 7 cm? (a) No (b) Yes
  22. 22.Can a triangle have sides of 3 cm, 7 cm and 15 cm? (a) No (b) Yes
  23. 23.In an isosceles triangle, the two equal angles are 64° each. What is the third angle (in degrees)?
  24. 24.The two interior opposite angles of a triangle are 77° and 20°. What is the exterior angle (in degrees)?
  25. 25.In triangle ABC, angle A = 85° and angle B = 41°. What is angle C (in degrees)?
  26. 26.In a right-angled triangle, one of the other two angles is 14°. What is the third angle (in degrees)?
  27. 27.Can a triangle have sides of 7 cm, 9 cm and 20 cm? (a) No (b) Yes
  28. 28.In an isosceles triangle, the angle between the two equal sides is 22°. What is each of the other two angles (in degrees)?
  29. 29.Can a triangle have sides of 8 cm, 6 cm and 15 cm? (a) No (b) Yes
  30. 30.In an isosceles triangle, the two equal angles are 27° each. What is the third angle (in degrees)?
  31. 31.An exterior angle of a triangle is 116°. One of its two interior opposite angles is 59°. What is the other one (in degrees)?
  32. 32.In a right-angled triangle, one of the other two angles is 25°. What is the third angle (in degrees)?
  33. 33.In triangle ABC, angle A = 69° and angle B = 82°. What is angle C (in degrees)?
  34. 34.An exterior angle of a triangle is 74°. One of its two interior opposite angles is 53°. What is the other one (in degrees)?
  35. 35.In triangle ABC, angle A = 91° and angle B = 37°. What is angle C (in degrees)?
  36. 36.In triangle ABC, angle A = 21° and angle B = 28°. What is angle C (in degrees)?
  37. 37.In an isosceles triangle, the two equal angles are 41° each. What is the third angle (in degrees)?
  38. 38.In triangle ABC, angle A = 90° and angle B = 59°. What is angle C (in degrees)?
  39. 39.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 50°. What is the third angle (in degrees)?

Answer key

  1. 79
  2. 69
  3. 17
  4. 72
  5. Yes
  6. Yes
  7. 7
  8. 60
  9. 54
  10. 42
  11. 112
  12. 121
  13. 36
  14. 120
  15. 64
  16. No
  17. 100
  18. 26
  19. 127
  20. 57
  21. Yes
  22. No
  23. 52
  24. 97
  25. 54
  26. 76
  27. No
  28. 79
  29. No
  30. 126
  31. 57
  32. 65
  33. 29
  34. 21
  35. 52
  36. 131
  37. 98
  38. 31
  39. 90
  40. 40

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