The area of the triangle formed by the pair of straight lines $(ax+by)^2-3(bx-ay)^2=0$ and $ax+by+c=0$, is :

Question

$$\begin {array} {1 1} (a)\;\frac{c^2}{a^2+b^2} & \quad (b)\;\frac{c^2}{2(a^2+b^2)} \\ (c)\;\frac{c^2}{\sqrt 2 (a^2+b^2)} & \quad (d)\;\frac{c^3}{\sqrt 3 (a^2+b^2)} \end {array}$$