$\begin{array}{1 1}\large\frac{4}{3}[8\pi-\sqrt 3] sq.units \\ \large\frac{4}{3}[8\pi+\sqrt 3] sq.units \\\large\frac{4}{3}[8\pi-\sqrt 5] sq.units. \\ \large\frac{2}{3}[8\pi-\sqrt 3] sq.units \end{array} $