Question

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

Answer 1

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 `2pi` the corresponding value of `r`, calculated as:
`r=cos(theta)`

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)