Can you help me find an expression for h please

Question

marigirl · Answer

attachment

marigirl · Answer

SO far i have 
$$\frac{ 40-x }{ r }=\frac{ 40 }{ 20 }$$

phi · Answer

assuming h is the height of the cylinder

marigirl · Answer

What must the radius of the cylinder be to give the cylinder the maximum volume is my question..

marigirl · Answer

$$v=\pi r^2 h$$
so an expression to sub into h

phi · Answer

I am not awake!
the proportion is
$$ \frac{40-h}{r}= \frac{40}{20} $$

marigirl · Answer

ok great so i was on the right track. ill go ahead and differentiate now :)

marigirl · Answer

why did u choose 40-h .....where as i did 40-x

marigirl · Answer

or are we talking about the same things?

phi · Answer

it depends what you mean by "x"
I used h because h is the height of the cylinder

marigirl · Answer

so then when you did 40-h you meant 40-height of cylinder...so we are left with the top part of cylinder

phi · Answer

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