Geometry
posted by Sarah .
Infinitely many different sectors can be cut from a circular piece of paper with a 12cm radius, and any such sector can be fashioned into a paper cone with a 12cm slant height.
(a) Show that the volume of the cone produced by the 180degree sector is larger than the volume of the cone produced by the 120degree sector.
(b) Find a sector of the same circle that will produce a cone whose volume is even larger.
(c) Express the volume of a cone formed from this circle as a function of the central angle of the sector used to form it, then find the sector that produces the cone of greatest volume.

Reiny answered this for you a couple of days ago.
http://www.jiskha.com/display.cgi?id=1271347261