For a regular 8 sided polygon each angle against each side, is 360/8=45.
So x=45/2=22.5
Then
[tex] \tan(22.5) = \frac{y}{8} \\ and \: we \: know \: \tan(22.5) = \ \sqrt[]{2} - 1 \\ so \: y = 8( \sqrt[]{2} - 1)[/tex]
