$\begin{array}{1 1} (a)\;225 \sqrt 3 m^2 \\ (b)\;\large\frac{225 \sqrt 3}{2}m^2 \\ (c)\;\large\frac{225 \sqrt 3}{4}m^2 \\ (d)\;\large\frac{225 \sqrt 3}{8}m^2 \end{array} $