put(r,−θ)in first equation will give the same function so it is symmetric about X-asis
Then chose the values for theta as0,π/6,π/2,....you will get the value of r
r=1-2 cos theta is a bit tricky to graph because r represents radius and we normally think of radius as being zero or positive. You could find the domain on which0≤1−2cosθand graph that section of the curve first, figuring out what to do with negative r later.