Use the Chain Rule to evaluate the partial derivative $\frac{\partial g}{\partial \theta}$ at the point $(r,\theta)=(2\sqrt 2,\frac{\pi}4)$
where $g(x,y) = \frac{1}{2 x+6 y^2}$, $x=r\sin\theta$, $y=r\cos\theta$.

$\frac{\partial g}{\partial \theta }\bigg|_{( r,\theta )= \left(2\sqrt{2},\frac{\pi }{4}\right)}=$