Let C 1 be the curve obtained by the solution of differential equation $2 x y \frac{d y}{d x}=y^2-x^2, x>0$. Let the curve $C_2$ be the solution of $\frac{2 x y}{x^2-y^2}=\frac{d y}{d x}$. If both the curves pass through $(1,1)$, then the area enclosed by the curves $\mathrm{C}_1$ and $\mathrm{C}_2$ is equal to: