cylinder arithmetic geometric mean

yaszine

New member
Joined
Oct 30, 2006
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17
hello,
please guys i need your help for this problem as part of my final preparation:

Use the arithmetic-geometric mean inequality to find the radius of a cylinder with
prescribed surface area and the largest possible volume.
Hints: The volume and the surface area of a cylinder of height h and radius r are given
use V = Pi*h*r^2 and S = 2*pi*r^2 + 2*pi*r*h, respectively. Eliminate h.

i tried doing that but all i could do is use calculus and calculated V in function of S and r, and put that V is maximum means that V' = 0 and calculated r in function of S.

i found r= cubic root of (-S/3*pi)

is there any way to do this using arithmetic geometric mean?!
thank you very much!
 
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