OCTA=8, an octagon has 8 sides, thus if one side is 6mm, then all sides, namely the perimeter, is 6+6+6+6+6+6+6+6, or 48.
now, we know what the apothem is.
[tex]\bf \textit{area of a regular polygon}\\\\
A=\cfrac{1}{2}ap~~
\begin{cases}
a=apothem\\
p=perimeter\\
-------\\
p=48\\
a=7.243
\end{cases}\implies A=\cfrac{1}{2}(7.243)(48)[/tex]
