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

Question

$\begin{array}{1 1} \large\frac{3b}{2a} \\\large\frac{b}{2a} \\ \large\frac{-b}{a} \\ \large\frac{b}{a} \end{array} $