Answer :
no thats not enough info you don know if 18 is the permitter of just one side of the shape .
Yes because if u divide it by 9 then each side is 2 inches then after that find the apothem by drawing A line from the center to the midpoint of 1 side then use the 30 60 90. After that use the formula 1/2ap then u know how to find it. Hope this helps. Here is a drawing to show u the example. Hope this helps.
