Sunday

March 1, 2015

March 1, 2015

Posted by **sonia** on Sunday, April 28, 2013 at 3:47am.

- math -
**Reiny**, Sunday, April 28, 2013 at 12:08pmradius -- r

height --- h

given: πr^2 h = 21

h = 21/(πr^2)

Surface area (SA) = 2πr^2 + 2πrh

= 2πr^2 + 2πr(21/(πr^2)

= 2πr^2 + 42/r

d(SA)/dr = 4πr - 42/r^2

= 0 for a max/min of SA

4πr = 42/r^2

r^3 = 42/(4π)

r = (42/(4π)^(1/3) = 1.495163.. or appr 1.5

then h = 21/(πr^2) = 2.99027 or appr 3

notice the h = 2r

**Answer this Question**

**Related Questions**

math - the volume of an cylindrical can with a radius r cm and height h cm is ...

Math - Optimization Problem A right circular cylindrical can of volume 128tπ...

Math 11 Surface area, Volume and Capacity - A cylindrical tin can has a radius ...

algebra/geometry please correct me - You need to make a soda can with a volume ...

geometry - a cylindrical soup can has a volume of 335cm^3.find the dimensions(...

maths --Surface area and all that.. - A toy is in the shape of a right circular ...

geometry/algebra - I asked this question yesterday, and I'm trying to understand...

calc - the volume of a cylindrical tin can with a top and a bottom is to be 16*...

Geometry - Find the volume of a right circular cylinder with a radius of 14in ...

Math - A cylindrical tin can has a radius of 4.5cm and a height of 5 cm (a)What ...