\[ y''(x)=2 y(x) \csc ^2(x) \] ✓ Mathematica : cpu = 0.0805171 (sec), leaf count = 58
\[\left \{\left \{y(x)\to \frac {c_1 \cos (x)}{\sqrt {\cos ^2(x)-1}}+\frac {c_2 \left (\cos (x) \left (-\sin ^{-1}(\cos (x))\right )-\sqrt {1-\cos ^2(x)}\right )}{\sqrt {1-\cos ^2(x)}}\right \}\right \}\] ✓ Maple : cpu = 0.242 (sec), leaf count = 50
\[\left \{y \left (x \right ) = \frac {-i c_{2} \ln \left (\cos \left (2 x \right )+i \sin \left (2 x \right )\right ) \sin \left (2 x \right )+c_{1} \sin \left (2 x \right )+2 c_{2} \left (\cos \left (2 x \right )-1\right )}{\cos \left (2 x \right )-1}\right \}\]