Let f be a continuous and differentiable function in `(x_(1),x_(2))`. If `f(x).f'(x)ge x sqrt(1-(f(x))^(4))` and `underset(xrarrx_(1))(lim)(f(x))^(2)=1 and underset(xrarrx)(lim)(f(x))^(2)=(1)/(2)`, then minimum value of `(x_(1)^(2)-x_(2)^(2))` is