Geometry puzzle

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Across
  1. 2. a shape with 3 sides
  2. 6. opposite over hypotenuse
  3. 7. 7 Sides
  4. 9. a quadrilateral with a right angle and 1 pair of parallel sides
  5. 12. Csquared=Asquared+bsquared
  6. 13. c squared = a squared + b squared - 2abcos(C)
  7. 17. sin(A)/a=Sin(B)/b=Sin(C)/c
  8. 19. 5 Sides
  9. 20. 6 sides
Down
  1. 1. a quadrilateral with one pair of parallel sides and 2 equal sides
  2. 3. a quadrilateral with 4 equal angles and 2 equal sides
  3. 4. a quadrilateral with 4 equal sides
  4. 5. adjacent over hypotenuse
  5. 8. shape with no angles
  6. 10. opposite over adjacent
  7. 11. 10 Sides
  8. 14. 8 Sides
  9. 15. a quadrilateral with 4 equal sides and 4 equal angles
  10. 16. a quadrilateral with 2 pairs of adjsent equal sides
  11. 18. 9 Sides