\[ \boxed { {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) +y \left ( x \right ) \tan \left ( x \right ) -\sin \left ( 2\,x \right ) =0} \]
Mathematica: cpu = 0.024003 (sec), leaf count = 17 \[ \left \{\left \{y(x)\to c_1 \cos (x)-2 \cos ^2(x)\right \}\right \} \]
Maple: cpu = 0.0 (sec), leaf count = 15 \[ \left \{ y \left ( x \right ) =-2\, \left ( \cos \left ( x \right ) \right ) ^{2}+\cos \left ( x \right ) {\it \_C1} \right \} \]
Sage: cpu = 0.004 (sec), leaf count = 0 \[ \left [\frac {c - 2 \, \cos \left (x\right )}{\sec \left (x\right )}, \text {\texttt {linear}}\right ] \]