\[
\boxed{
{\frac {\rm d}{{\rm d}x}}y \left( x \right) =-{\frac {\cos \left( y \left( x \right)  \right)  \left( x-\cos \left( y \left( x \right)  \right) +1 \right) }{ \left( x\sin \left( y \left( x \right)  \right) -1 \right)  \left( 1+x \right) }}=0}
\]