1. Sketch polar

how do i sketch this polar equation r = 1 - 2 cos theta

2. Hello, reiward!

How do i sketch this polar equation? . $r \:=\:1 - 2\cos\theta$

You should be familiar with the curve called the limacon.
. . This one has a "loop".

Calculate a few ponts:

. . $\begin{array}{|c|c|}
\theta & r \\ \hline
0 & \text{-}1 \\ \frac{\pi}{2} & 1 \\ \pi & 3 \\ \frac{3\pi}{2} & 1 \end{array}$

The graph looks like this:
Code:
:
* * o 1
*       : *
*         :   *
*          :   *
:  *
*      * *  : *
- - o - - o - - * - - - -
3 *   -1 * *  : *
:  *
*          :   *
*         :   *
*       : *
* * o 1
: