\[
\boxed{
 \left( {\frac {\rm d}{{\rm d}x}}y \left( x \right)  \right) \cos \left( y \left( x \right)  \right) -\cos \left( x \right)  \left( \sin \left( y \left( x \right)  \right)  \right) ^{2}-\sin \left( y \left( x \right)  \right) =0}
\]