\[ y'(x)^2 \sin (y(x))+2 x y'(x) \cos ^3(y(x))-\sin (y(x)) \cos ^4(y(x))=0 \] ✓ Mathematica : cpu = 0.0790237 (sec), leaf count = 81
\[\left \{\left \{y(x)\to \tan ^{-1}\left (2 \left (-\frac {c_1{}^{3/2}}{\sqrt {x+c_1}}-\frac {\sqrt {c_1} x}{\sqrt {x+c_1}}\right )\right )\right \},\left \{y(x)\to \tan ^{-1}\left (2 \left (\frac {c_1{}^{3/2}}{\sqrt {x+c_1}}+\frac {\sqrt {c_1} x}{\sqrt {x+c_1}}\right )\right )\right \}\right \}\] ✓ Maple : cpu = 4.842 (sec), leaf count = 1134
\[ \left \{ [x \left ( {\it \_T} \right ) ={\frac {1}{2\,{\it \_T}} \left ( \left ( \cos \left ( {\frac {1}{2}\arctan \left ( { \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}-2\,{\it \_T}\,{\it \_C1}\,\sqrt [3]{{{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) }}+ \left ( {{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) } \right ) ^{{\frac {2}{3}}} \right ) {\frac {1}{\sqrt [3]{{{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) }}}}},-9\,{\frac {1/3\, \left ( {{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) } \right ) ^{2/3}+ \left ( {\it \_T}\,{\it \_C1}+1/9\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) } \right ) \left ( {\it \_T}\,{\it \_C1}-\sqrt [3]{{{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) }} \right ) }{ \left ( {{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) } \right ) ^{2/3}}} \right ) } \right ) \right ) ^{4}-{{\it \_T}}^{2} \right ) \sin \left ( {\frac {1}{2}\arctan \left ( { \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}-2\,{\it \_T}\,{\it \_C1}\,\sqrt [3]{{{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) }}+ \left ( {{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) } \right ) ^{{\frac {2}{3}}} \right ) {\frac {1}{\sqrt [3]{{{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) }}}}},-9\,{\frac {1/3\, \left ( {{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) } \right ) ^{2/3}+ \left ( {\it \_T}\,{\it \_C1}+1/9\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) } \right ) \left ( {\it \_T}\,{\it \_C1}-\sqrt [3]{{{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) }} \right ) }{ \left ( {{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) } \right ) ^{2/3}}} \right ) } \right ) \left ( \cos \left ( {\frac {1}{2}\arctan \left ( { \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}-2\,{\it \_T}\,{\it \_C1}\,\sqrt [3]{{{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) }}+ \left ( {{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) } \right ) ^{{\frac {2}{3}}} \right ) {\frac {1}{\sqrt [3]{{{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) }}}}},-9\,{\frac {1/3\, \left ( {{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) } \right ) ^{2/3}+ \left ( {\it \_T}\,{\it \_C1}+1/9\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) } \right ) \left ( {\it \_T}\,{\it \_C1}-\sqrt [3]{{{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) }} \right ) }{ \left ( {{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) } \right ) ^{2/3}}} \right ) } \right ) \right ) ^{-3}},y \left ( {\it \_T} \right ) ={\frac {1}{2}\arctan \left ( { \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}-2\,{\it \_T}\,{\it \_C1}\,\sqrt [3]{{{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) }}+ \left ( {{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) } \right ) ^{{\frac {2}{3}}} \right ) {\frac {1}{\sqrt [3]{{{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) }}}}},-9\,{\frac {1/3\, \left ( {{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) } \right ) ^{2/3}+ \left ( {\it \_T}\,{\it \_C1}+1/9\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) } \right ) \left ( {\it \_T}\,{\it \_C1}-\sqrt [3]{{{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) }} \right ) }{ \left ( {{\it \_C1}}^{3}{{\it \_T}}^{3}+54\,{\it \_T}\,{\it \_C1}+6\,\sqrt {3}\sqrt {{{\it \_C1}}^{2}{{\it \_T}}^{2} \left ( {{\it \_C1}}^{2}{{\it \_T}}^{2}+27 \right ) } \right ) ^{2/3}}} \right ) }] \right \} \]