Use a graphing utility to convince yourself that the polar equations r = 1 () =

Use a graphing utility to convince yourself that the polar equations r = ƒ₁(θ) = 2 cos θ − 1 and r = ƒ₂(θ) = 2 cos θ + 1 have the same graph. Then explain why. Show that the points (ƒ₁(θ + π), θ + π) and (ƒ₂(θ), θ) coincide.