If $x$ and $y$ are connected parametrically by the equations given in $x = a ( \theta - \sin \theta ), y = a ( 1 +\cos \theta) $ without eliminating the parameter, Find $\large\frac{dy}{dx}$

Question

$\begin{array}{1 1} \cot\large\frac{\theta}{2} \\ -\cot\large\frac{\theta}{2} \\ -\cot\large\frac{\theta}{4} \\ -\tan\large\frac{\theta}{2}\end{array} $