Can anybody explain what $\tan(\sin^{-1}(\frac x y))$ equals?
I have to determine whether $y'' \left(\tan \left(\sin^{-1}\left(\frac x y \right)\right) - \frac{x}{\sqrt{y^2-x^2}} \right)=0$ is a linear differential equation. I thought that the left term might be equal to the right term, but I guess not.