3 A curve \(C\) has polar equation \(r ( 1 + \cos \theta ) = 2\).
- Find the cartesian equation of \(C\), giving your answer in the form \(y ^ { 2 } = \mathrm { f } ( x )\).
- The straight line with polar equation \(4 r = 3 \sec \theta\) intersects the curve \(C\) at the points \(P\) and \(Q\). Find the length of \(P Q\).