1. The problem statement, all variables and given/known data 2. Relevant equations 3. The attempt at a solution c=0.06(pie)r^2+0.06(pie)r(k/pie(r^2)) c'=0.06(pie)r - 0.06kr^-2 r^3=k^1/3 / (pie^1/3) h/r= 1/1 I'm not sure if what I did here is right. I didn't put all the steps up there.