\dfrac{dy}{dx}=\dfrac{\sin \left( a+y \right)}{\cos y-x.\cos \left( a+y \right)}
Find \dfrac{{dy}}{{dx}},x = a\left( {\cos t + \log \tan \frac{t}{2}} \right),y = a\sin t
If \sin y = x \sin (a + y), then prove that \dfrac{dy}{dx} = \dfrac{\sin^2 (a+y)}{\sin a}.