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LauraJane
Oct4-05, 09:10 PM
Q: a cone shaped paper drinking cup holds 10 cubic cm of water. We would like to find the height and radius that will require the least amount of paper.

Volume of a cone is: (b x h)/3, or with radius is: ((pi r squared x h))/3.

I think you solve this problem by finding a ratio and getting h in terms of r. Any ideas? Thank you!

amcavoy
Oct4-05, 09:57 PM
Q: a cone shaped paper drinking cup holds 10 cubic cm of water. We would like to find the height and radius that will require the least amount of paper.

Volume of a cone is: (b x h)/3, or with radius is: ((pi r squared x h))/3.

I think you solve this problem by finding a ratio and getting h in terms of r. Any ideas? Thank you!
You know:

\text{V}=\frac{\pi\,r^{2}\,h}{3}=10

If I remember correctly, the surface area (what you want to minimize) is:

\text{S}=\pi\,r\,\sqrt{r^{2}+h^{2}}

Now minimize this taking into consideration the restraint on volume.