# Defining a domain of cardioid region in terms of polar coordinates.

Consider the region contained inside both the cardioid $r=1+\cos\theta$ and outside the circle $r=3\cos\theta$, where $r$ and $\theta$ are polar coordinates. So weirdly enough I know how to calculate the area itself, but the question wants me to define the domain of this region in terms of polar coordinates???

Since I have two distinct regions, one above and one below the axis, how could I define the domain? I was thinking of using union/intersection but it didn't work. Thanks

$$3\, c = c, c = cos \, \theta =\frac12, \theta = \pm (\pi/3 ) ,$$ which is the domain symmetric to x axis.