# Math Help - function of cylinder

1. ## 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...

2. 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: $A=2\pi r^2+2\pi rh$

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

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

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

Anyway, your job is to solve for h.

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

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

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

Which can be simplified to:

h = [A/(2*Pi*r)] - r

4. Originally Posted by Quick
it's pi, not pie...
I always laugh when I see that "pie"...

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

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

$\pi$ is pronunced as "pee" not "pie".
My guess is that users with native English speech pronunce $\pi$ 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 $\xi$. 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