← 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 174 · 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 triangle ABC, angle A = 22° and angle B = 36°. What is angle C (in degrees)?
  2. 2.In triangle ABC, angle A = 100° and angle B = 37°. What is angle C (in degrees)?
  3. 3.Can a triangle have sides of 12 cm, 10 cm and 10 cm? (a) No (b) Yes
  4. 4.In triangle ABC, angle A = 52° and angle B = 69°. What is angle C (in degrees)?
  5. 5.The two interior opposite angles of a triangle are 70° and 29°. What is the exterior angle (in degrees)?
  6. 6.An exterior angle of a triangle is 61°. One of its two interior opposite angles is 21°. What is the other one (in degrees)?
  7. 7.The longest side of a right-angled triangle is 26 cm and one of the other sides is 24 cm. How long is the third side (in cm)?
  8. 8.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  9. 9.An exterior angle of a triangle is 97°. One of its two interior opposite angles is 71°. What is the other one (in degrees)?
  10. 10.The two shorter sides of a right-angled triangle are 12 cm and 5 cm. How long is the longest side (in cm)?
  11. 11.In an isosceles triangle, the two equal angles are 72° each. What is the third angle (in degrees)?
  12. 12.In an isosceles triangle, the two equal angles are 26° each. What is the third angle (in degrees)?
  13. 13.In triangle ABC, angle A = 41° and angle B = 30°. What is angle C (in degrees)?
  14. 14.The two interior opposite angles of a triangle are 75° and 44°. What is the exterior angle (in degrees)?
  15. 15.In a right-angled triangle, one of the other two angles is 11°. What is the third angle (in degrees)?
  16. 16.Can a triangle have sides of 19 cm, 7 cm and 7 cm? (a) No (b) Yes
  17. 17.The two interior opposite angles of a triangle are 33° and 65°. What is the exterior angle (in degrees)?
  18. 18.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  19. 19.Can a triangle have sides of 11 cm, 2 cm and 5 cm? (a) Yes (b) No
  20. 20.In triangle ABC, angle A = 65° and angle B = 65°. What is angle C (in degrees)?
  21. 21.The angles of a triangle are in the ratio 3 : 3 : 4. What is the biggest angle (in degrees)?
  22. 22.Can a triangle have sides of 11 cm, 13 cm and 10 cm? (a) No (b) Yes
  23. 23.Can a triangle have sides of 6 cm, 12 cm and 7 cm? (a) No (b) Yes
  24. 24.An exterior angle of a triangle is 88°. One of its two interior opposite angles is 25°. What is the other one (in degrees)?
  25. 25.In triangle ABC, angle A = 47° and angle B = 60°. What is angle C (in degrees)?
  26. 26.The angles of a triangle are in the ratio 1 : 1 : 2. What is the biggest angle (in degrees)?
  27. 27.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)?
  28. 28.In an isosceles triangle, the angle between the two equal sides is 34°. What is each of the other two angles (in degrees)?
  29. 29.An exterior angle of a triangle is 111°. One of its two interior opposite angles is 75°. What is the other one (in degrees)?
  30. 30.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  31. 31.In triangle ABC, angle A = 76° and angle B = 55°. What is angle C (in degrees)?
  32. 32.Can a triangle have sides of 9 cm, 10 cm and 24 cm? (a) Yes (b) No
  33. 33.The two shorter sides of a right-angled triangle are 15 cm and 8 cm. How long is the longest side (in cm)?
  34. 34.In triangle ABC, angle A = 69° and angle B = 69°. What is angle C (in degrees)?
  35. 35.In an isosceles triangle, the angle between the two equal sides is 146°. What is each of the other two angles (in degrees)?
  36. 36.The angles of a triangle are in the ratio 3 : 5 : 7. What is the biggest angle (in degrees)?
  37. 37.In triangle ABC, angle A = 24° and angle B = 72°. What is angle C (in degrees)?
  38. 38.The angles of a triangle are in the ratio 2 : 3 : 5. What is the biggest angle (in degrees)?
  39. 39.In triangle ABC, angle A = 58° and angle B = 37°. What is angle C (in degrees)?
  40. 40.In an isosceles triangle, the two equal angles are 20° each. What is the third angle (in degrees)?

Answer key

  1. 122
  2. 43
  3. Yes
  4. 59
  5. 99
  6. 40
  7. 10
  8. 25
  9. 26
  10. 13
  11. 36
  12. 128
  13. 109
  14. 119
  15. 79
  16. No
  17. 98
  18. 17
  19. No
  20. 50
  21. 72
  22. Yes
  23. Yes
  24. 63
  25. 73
  26. 90
  27. 8
  28. 73
  29. 36
  30. 75
  31. 49
  32. No
  33. 17
  34. 42
  35. 17
  36. 84
  37. 84
  38. 90
  39. 85
  40. 140

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