← 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 717 · 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 = 97° and angle B = 28°. What is angle C (in degrees)?
  2. 2.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  3. 3.In triangle ABC, angle A = 69° and angle B = 35°. What is angle C (in degrees)?
  4. 4.In an isosceles triangle, the two equal angles are 25° each. What is the third angle (in degrees)?
  5. 5.In a right-angled triangle, one of the other two angles is 63°. What is the third angle (in degrees)?
  6. 6.In an isosceles triangle, the two equal angles are 45° each. What is the third angle (in degrees)?
  7. 7.The two interior opposite angles of a triangle are 50° and 31°. What is the exterior angle (in degrees)?
  8. 8.In triangle ABC, angle A = 34° and angle B = 89°. What is angle C (in degrees)?
  9. 9.In triangle ABC, angle A = 37° and angle B = 35°. What is angle C (in degrees)?
  10. 10.In triangle ABC, angle A = 50° and angle B = 37°. What is angle C (in degrees)?
  11. 11.The angles of a triangle are in the ratio 1 : 4 : 5. What is the smallest angle (in degrees)?
  12. 12.In triangle ABC, angle A = 89° and angle B = 48°. What is angle C (in degrees)?
  13. 13.In triangle ABC, angle A = 68° and angle B = 78°. What is angle C (in degrees)?
  14. 14.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)?
  15. 15.The two interior opposite angles of a triangle are 47° and 71°. What is the exterior angle (in degrees)?
  16. 16.In an isosceles triangle, the two equal angles are 85° each. What is the third angle (in degrees)?
  17. 17.The angles of a triangle are in the ratio 1 : 4 : 5. What is the biggest angle (in degrees)?
  18. 18.In an isosceles triangle, the two equal angles are 46° each. What is the third angle (in degrees)?
  19. 19.In an isosceles triangle, the two equal angles are 52° each. What is the third angle (in degrees)?
  20. 20.In an isosceles triangle, the two equal angles are 74° each. What is the third angle (in degrees)?
  21. 21.In triangle ABC, angle A = 96° and angle B = 60°. What is angle C (in degrees)?
  22. 22.Can a triangle have sides of 11 cm, 21 cm and 9 cm? (a) Yes (b) No
  23. 23.The angles of a triangle are in the ratio 1 : 1 : 2. What is the smallest angle (in degrees)?
  24. 24.Can a triangle have sides of 12 cm, 3 cm and 20 cm? (a) No (b) Yes
  25. 25.In triangle ABC, angle A = 79° and angle B = 35°. What is angle C (in degrees)?
  26. 26.The angles of a triangle are in the ratio 1 : 3 : 5. What is the smallest angle (in degrees)?
  27. 27.An exterior angle of a triangle is 103°. One of its two interior opposite angles is 40°. What is the other one (in degrees)?
  28. 28.In triangle ABC, angle A = 70° and angle B = 81°. What is angle C (in degrees)?
  29. 29.The two shorter sides of a right-angled triangle are 8 cm and 15 cm. How long is the longest side (in cm)?
  30. 30.In triangle ABC, angle A = 41° and angle B = 25°. What is angle C (in degrees)?
  31. 31.In an isosceles triangle, the angle between the two equal sides is 136°. What is each of the other two angles (in degrees)?
  32. 32.In triangle ABC, angle A = 30° and angle B = 20°. What is angle C (in degrees)?
  33. 33.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  34. 34.Can a triangle have sides of 10 cm, 6 cm and 18 cm? (a) Yes (b) No
  35. 35.The two interior opposite angles of a triangle are 33° and 44°. What is the exterior angle (in degrees)?
  36. 36.The two interior opposite angles of a triangle are 27° and 76°. What is the exterior angle (in degrees)?
  37. 37.In triangle ABC, angle A = 72° and angle B = 83°. What is angle C (in degrees)?
  38. 38.The angles of a triangle are in the ratio 2 : 2 : 5. What is the biggest angle (in degrees)?
  39. 39.The angles of a triangle are in the ratio 3 : 3 : 4. What is the smallest angle (in degrees)?
  40. 40.In a right-angled triangle, one of the other two angles is 62°. What is the third angle (in degrees)?

Answer key

  1. 55
  2. 20
  3. 76
  4. 130
  5. 27
  6. 90
  7. 81
  8. 57
  9. 108
  10. 93
  11. 18
  12. 43
  13. 34
  14. 15
  15. 118
  16. 10
  17. 90
  18. 88
  19. 76
  20. 32
  21. 24
  22. No
  23. 45
  24. No
  25. 66
  26. 20
  27. 63
  28. 29
  29. 17
  30. 114
  31. 22
  32. 130
  33. 36
  34. No
  35. 77
  36. 103
  37. 25
  38. 100
  39. 54
  40. 28

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