Solution
= Solution
The operator $R_g$ reverses the $|\psi_g\rangle$ component and fixes $|\psi_b\rangle$, so it is reflection in the horizontal $|\psi_b\rangle$ axis. The operator $R_{|\Omega\rangle}$ reverses the component parallel to $|\Omega\rangle$ and fixes its perpendicular line; multiplication by $-1$ reverses those roles. Hence $-R_{|\Omega\rangle}$ is reflection in the line spanned by $|\Omega\rangle$.