Find the area of equilateral triangle inscribed in the circle $x^2+y^2+2gx+2fy+c=0$?

Question

$\begin{array}{1 1}(a)\;\large\frac{3\sqrt 3}{2}\normalsize (g^2-f^2+c)sq.units\\(b)\;\large\frac{3\sqrt 3}{4}\normalsize (g^2+f^2-c)sq.units\\(c)\;\large\frac{\sqrt 3}{2}\normalsize (g^2-f^2+c)sq.units\\(d)\;\large\frac{3\sqrt 5}{2}\normalsize (g^2+f^2+c)sq.units\end{array}$