Arcsin as inverse sine
From specialfunctionswiki
Theorem
The restricted arcsin function $\rm{arcsin} \colon [-1,1] \rightarrow \left[ -\dfrac{\pi}{2}, \dfrac{\pi}{2} \right]$ is the inverse function of the restricted sine function $\sin \colon \left[ -\dfrac{\pi}{2}, \dfrac{\pi}{2} \right] \rightarrow [-1,1]$.