The range of the real valued function \( f(x) =\) \(\sin^{-1} \left( \frac{1 + x^2}{2x} \right)\) \(+ \cos^{-1} \left( \frac{2x}{1 + x^2} \right)\) is:
If \( y = \tan(\log x) \), then \( \frac{d^2y}{dx^2} \) is given by: