Solution
= Solution
For <spherical coordinates>, the distance from the origin is $\sqrt{26}$ and the polar angle satisfies $\cos\theta=z/r=-1/\sqrt{26}$. The azimuth is the same as in part (a). Thus
$$
\boxed{(r,\theta,\phi)=\left(\sqrt{26},\ \arccos\left(-\frac1{\sqrt{26}}\right),\ \pi+\arctan\frac43\right)}.
$$
The polar angle is in $(\pi/2,\pi)$ because the point lies below the $xy$-<plane>.