# Area of circle in polar coordinates

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1. Dec 13, 2014

### Malabeh

1. The problem statement, all variables and given/known data
r=2cos(theta) I want to find the area using polar integration.

2. Relevant equations
area=(1/2)r^2 from 0-pi

3. The attempt at a solution
When I plug everything in I get 2pi as the answer. I'm in multivariable calculus so this is very frustrating. What am I doing wrong, I don't know, but it's really really really really bugging me. I have an extra 2 somewhere and I don't know where.

2. Dec 13, 2014

### Malabeh

EDIT: I don't know how to delete a post but I got it. My calculator was in degree mode.

3. Dec 13, 2014

### LCKurtz

While you may have gotten the correct answer, if you plot that circle you will see that the appropriate interval of integration would be $[-\frac \pi 2,\frac \pi 2]$, not $[0,\pi]$.

4. Dec 13, 2014

### Malabeh

It works both ways, does it not?