Derivation of volumes??

Question

Can sum1 please post the derivation for the formulae for
1. volume of a cone and
2. both circular and squared based frustrums

Please keep it simple, thanks

Answer 1

1. Height: h; Radius of base: r
V = Pi r^2 . (h/3)
2. for circular, difference between two cylinders,
V = Pi (ra)^2 . (h)/3 - Pi (rb)^2 . (rb/ra) . (h/3)
Height: ha; Radius of bottom base: rb; Radius of top base: rb

similar relationship are true for square bases

Answer 2

Type 'geometry volume' in the search window and you will get over 1.3 million hits.

You wade through them ☺


Doug