\[ \boxed { \left ( {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) \right ) \sin \left ( y \left ( x \right ) \right ) \cos \left ( x \right ) +\cos \left ( y \left ( x \right ) \right ) \sin \left ( x \right ) =0} \]
Mathematica: cpu = 0.043506 (sec), leaf count = 29 \[ \left \{\left \{y(x)\to -\cos ^{-1}\left (\frac {1}{2} c_1 \sec (x)\right )\right \},\left \{y(x)\to \cos ^{-1}\left (\frac {1}{2} c_1 \sec (x)\right )\right \}\right \} \]
Maple: cpu = 0.062 (sec), leaf count = 11 \[ \left \{ y \left ( x \right ) =\arccos \left ( {\frac {{\it \_C1}}{\cos \left ( x \right ) }} \right ) \right \} \]