\[ \boxed { {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) =-{\frac {\cos \left ( x \right ) {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) }{\sin \left ( x \right ) }}+{\frac {y \left ( x \right ) }{ \left ( \sin \left ( x \right ) \right ) ^{2}}}=0} \]
Mathematica: cpu = 0.056507 (sec), leaf count = 51 \[ \left \{\left \{y(x)\to c_1 \cosh \left (\log \left (\cos \left (\frac {x}{2}\right )\right )-\log \left (\sin \left (\frac {x}{2}\right )\right )\right )-i c_2 \sinh \left (\log \left (\cos \left (\frac {x}{2}\right )\right )-\log \left (\sin \left (\frac {x}{2}\right )\right )\right )\right \}\right \} \]
Maple: cpu = 0.031 (sec), leaf count = 25 \[ \left \{ y \left ( x \right ) ={\frac {\sin \left ( x \right ) {\it \_C1} }{-1+\cos \left ( x \right ) }}+{\frac { \left ( -1+\cos \left ( x \right ) \right ) {\it \_C2}}{\sin \left ( x \right ) }} \right \} \]