Respuesta :

[tex]\bf \textit{area of a regular polygon}\\\\ A=\cfrac{1}{2}ap~~ \begin{cases} a=apothem\\ p=perimeter\\[-0.5em] \hrulefill\\ a= 3\\ p=20 \end{cases}\implies A=\cfrac{1}{2}(3)(20)\implies A=30[/tex]