Expert: Ahmed Salami - 10/28/2010

Question
Could you please clarify the answer to this:
http://en.allexperts.com/q/Calculus-2063/2009/4/calculus-
finding-dimension-dorm.htm ?

I set up my equations like this:
V=(1/2)π(x^2)y=225000ft^2
Foundation SA=2xy=F
Sides SA=π(X^2)=S
Roof SA=πXY=R
Cost=30F+20S+15R

I don't know what I should do from there, should I find the
derivative to the cost function?

Answer
Hi Valerie,
Yes. You need to find the derivative of the cost function, and then equate to zero to get the optimum values.
There are two images attached to the initial solution, the first one clearly showing the step by step procedure. Just note that, in the solution,
b = 2x
l = y

Best of luck.

Regards