You can put this solution on YOUR website! This question is not quite clear.
I think the largest base circle has radus r =4 cm ( with diameter 8 cm)
and the height of the right ciecular cone is h = 8 cm.
Hence, the volume of the cone is pi r^2 h /3 = 128 pi/ 3 cm^3
(the approximated value is left for you if necessary.)
Kenny