\[
\boxed{
 \left( \sin \left( x \right)  \right) ^{2}{\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left( x \right) - \left( {a}^{2} \left( \cos \left( x \right)  \right) ^{2}+b\cos \left( x \right) +{\frac {{b}^{2}}{ \left( 2\,a-3 \right) ^{2}}}+3\,a+2 \right) y \left( x \right) =0}
\]