The angle of incidence at which reflected light is totally polarized for reflection from air to glass (refractive index $n$), is:

According to Brewster's Law, when light is incident at a specific angle (polarizing angle $i_p$) such that the reflected ray is totally polarized, the refractive index $n$ of the medium is equal to the tangent of that angle.
$$n=\tan i_p⟹i_p={\tan }^{-1}(n)$$