4 The parametric equations of a curve are
$$x = 2 \sin \theta + \sin 2 \theta , \quad y = 2 \cos \theta + \cos 2 \theta$$
where \(0 < \theta < \pi\).
- Obtain an expression for \(\frac { \mathrm { d } y } { \mathrm {~d} x }\) in terms of \(\theta\).
- Hence find the exact coordinates of the point on the curve at which the tangent is parallel to the \(y\)-axis.