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So I need to find the POI (point of intersection) of the following two curves: \begin{align*} r & = 1 + \cos \theta, \\ r & = 2 - 2\cos \theta. \end{align*} What I did was I just set both the equations equal to each other... $$1 + \cos \theta = 2 - 2 \cos \theta$$ then isolated for $\theta$ and found the angle, which is $70^\circ$... however I drew the two graphs (looks like both cardioids) and it looks like I have 2 POI's... so I'm not sure why I only get one angle when I solve for $\theta$?

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