From a thin metallic piece, in the shape of a trapezium $ABCD,$ in which $AB$ is parallel to $CD$ and $\angle BCD = 90^{\circ}$, a quarter circle $BEFC$ is removed. Given $AB = BC = 3.5\;cm$ and $DE = 2cm,$ calculate the area of the remaining piece of the metal sheet.

Question

$\begin{array}{1 1} 6 \;cm \\ 6.125\;cm^2 \\ 7.345\;cm^3 \\ 3.245\;cm^2 \end{array}$