Question

The formula for the volume of a cone is `V= 1/3 pi r^2h` with `pi =3.14` . How do you find the radius, to the nearest hundredth, of a cone with a height of 5 in. and a volume of `20" in"^3`?

Answer 1

`h~~1.95" inch (2dp)."`

Explanation:

`V=1/3pir^2h rArr r^2=(3V)/(pih) rArr r=sqrt{(3V)/(pih)}.`

With, `V=20 and h=5, r=sqrt[{(3)(20)}/(5pi)}=sqrt(12/pi)`

`=sqrt(3.8197)~~1.95" inch (2dp)."`