AMC 12 2012b Problem 10

What is the area of the polygon whose vertices are the points of intersection of the curves $x^2 + y^2 =25$ and $(x-4)^2 + 9y^2 = 81$?

\textbf{(A)}\ 24 \textbf{(B)}\ 27 \textbf{(C)}\ 36 \textbf{(D)}\ 37.5 \textbf{(E)}\ 42