Recall that the volume of a cylinder is given by
[tex]V=\pi\cdot r^2\cdot h[/tex]Where r is the radius and h is the height of the cylinder.
For the given case, we are given
V = 1296π cm³
h = 16 cm
Let us substitute these values into the above formula and solve for the radius
[tex]\begin{gathered} V=\pi\cdot r^2\cdot h \\ 1296\pi=\pi\cdot r^2\cdot16 \\ \frac{1296\pi}{16\pi}=r^2 \\ \frac{1296}{16}=r^2 \\ 81=r^2 \\ \sqrt{81}=r \\ 9=r \\ r=9\: cm \end{gathered}[/tex]Therefore, the length of the cylinder's radius is 9 cm