If the length of the three sides of a trapezium other than the base are equal to 10 cm , then find the area of the trapezium when it is maximum .

Question

$\begin{array}{1 1} 75\sqrt 3 \;cm^2 \\ \sqrt 5 cm^2 \\ 0 \\ 4\sqrt 2 cm^2 \end{array}$