# Find eqn of cylinder of height

1. Apr 24, 2012

### sharks

1. The problem statement, all variables and given/known data
How to find the equation of cylinder: $x^2+y^2=4$ from z=0 to z=2?

2. Relevant equations
$$(x-a)^2+(y-b)^2=r^2$$

3. The attempt at a solution
I can't figure out how to implement the z-coordinate into the general equation of cylinder. In the latter, the height is taken as infinite in both opposite directions (upward and downward).

2. Apr 24, 2012

### Staff: Mentor

Doesn't this work?
$x^2+y^2=4; 0 \leq z \leq 2$

3. Apr 24, 2012

### sharks

Hi Mark44!

Actually, that's how the equations are originally given in the problem but i was wondering if there is a way to combine those 2 into a single equation, since the height of the cylinder is known.

In my mind, maybe something like that: $x^2+y^2 + (z-c)^n=4$ even though it's now become closer to a sphere!

Last edited: Apr 24, 2012
4. Apr 24, 2012

### Staff: Mentor

No, there's no way to combine the equation and inequality into one.

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