Chapter 5.1, Problem 6P

${\displaystyle \int \frac{K\text{dr}}{r\sqrt{r^2-k^2}}{\cos }^{-1}\frac{k}{r}{\text{ or sec}}^{-1}\frac{r}{k}{\text{ or -sin}}^{-1}}\frac{k}{r}{\text{ or -tan}}^{-1}\frac{K}{\sqrt{r^2-k^2}}$