Since the circle is circumscribing the rectangle,the vertices of the rectangle lie on the circle.
We can consider the general eqn of circle and sub the given vertices ,Also the centre lies
on the given line.Sub the centre (-g,-f).Now solve for g and f.After g and f are found,we can
take the centre as the midpoint and and find the diametrically opposite ends of the given
vertices.By this we can get the remaining 2 vertices,Now,its easy to find area !