Derive the following corresponding expression for the Laplacian in spherical coordinates:

\[\begin{equation*}abla^{2} T=\frac{1}{r^{2}} \frac{\partial}{\partial r}\left(r^{2} \frac{\partial T}{\partial r}\right)+\frac{1}{r^{2} \sin \theta} \frac{\partial}{\partial \theta}\left(\sin \theta\frac{\partial T}{\partial \theta}\right)+\frac{1}{r^{2} \sin ^{2} \theta} \frac{\partial^{2} T}{\partial \phi^{2}} \tag{1.58}\end{equation*}\]