# What does the graph of r = \cos \theta such that 0^\circ \le \theta \le 360^\circ look like?

Dec 28, 2014

I used Excel to plot your graph and I got:

In the first two columns you have for each angle $\theta$ (in radians but it is the same) between $0$ and $2 \pi$ the corresponding value of $r$, calculated as:
$r = \cos \left(\theta\right)$

The next two columns contain the corresponding values of $x$ and $y$ to plot your equation on a rectangular coordinate system $x , y$.

To obtain the values in the $x$ and $y$ columns you must remember the relationship between polar (first two columns) and rectangular (second two columns) coordinates:

(hope it helped)