Chapter 14.6, Problem 26ES

Use a CAS to evaluate ${\displaystyle {\int }_0^{\pi /2}{\displaystyle {\int }_0^{\pi /4}{\displaystyle {\int }_0^{\cos \theta }{\rho }^{17}\cos \varphi {\cos }^{19}\theta d\rho d\varphi d\theta }}}$