Let \(\mathbf{e}_{\mathbf{r}}=\langle x / r, y / r, z / rangle\) be the unit radial vector, where \(r=\sqrt{x^{2}+y^{2}+z^{2}}\). Calculate the integral of \(\mathbf{F}=\) \(e^{-r} \mathbf{e}_{\mathbf{r}}\) over:
(a) the upper hemisphere of \(x^{2}+y^{2}+z^{2}=9\), outward-pointing normal.
(b) the octant \(x \geq 0, y \geq 0, z \geq 0\) of the unit sphere centered at the origin.