# function of cylinder

• Dec 4th 2006, 05:00 PM
eah1010
function of cylinder
the surface of a tin can, can be found by using formula A=2pie(r)^2 + 2 pie(r)h. A = Area R = Radius H = Height. Write h as a functoin of A and R

im real sorry guys im just not understanding this...
• Dec 4th 2006, 05:05 PM
Quick
Quote:

Originally Posted by eah1010
the surface of a tin can, can be found by using formula A=2pie(r)^2 + 2 pie(r)h. A = Area R = Radius H = Height. Write h as a functoin of A and R

im real sorry guys im just not understanding this...

it's pi, not pie...

Anyway, your job is to solve for h.

We have: $\displaystyle A=2\pi r^2+2\pi rh$

Then: $\displaystyle A-2\pi r^2=2\pi rh$

Divide: $\displaystyle \frac{A-2\pi r^2}{2\pi r}=h$

• Dec 4th 2006, 06:18 PM
AfterShock
Quote:

Originally Posted by Quick
it's pi, not pie...

Anyway, your job is to solve for h.

We have: $\displaystyle A=2\pi r^2+2\pi rh$

Then: $\displaystyle A-2\pi r^2=2\pi rh$

Divide: $\displaystyle \frac{A-2\pi r^2}{2\pi r}=h$

Which can be simplified to:

h = [A/(2*Pi*r)] - r
• Dec 5th 2006, 05:01 AM
OReilly
Quote:

Originally Posted by Quick
it's pi, not pie...

I always laugh when I see that "pie"...:)

$\displaystyle \pi$ is pronunced as "pee" not "pie".
My guess is that users with native English speech pronunce $\displaystyle \pi$ as "pie" because they spell "i" like in alphabet.
• Dec 5th 2006, 09:50 AM
topsquark
Quote:

Originally Posted by OReilly
I always laugh when I see that "pie"...:)

$\displaystyle \pi$ is pronunced as "pee" not "pie".
My guess is that users with native English speech pronunce $\displaystyle \pi$ as "pie" because they spell "i" like in alphabet.

Really? I didn't know that. I once had a 10 minute discussion with a guy on the correct way to pronounce $\displaystyle \xi$. He wasn't Greek himself, but had studied it a bit. (I had a Korean Physics professor who simply called it "squiggly." :) ) Of course, if I started talking to someone about "pee" they'd never understand I was talking about "pi."

-Dan