\[ \cos (x) y'(x) \sin (y(x))+\sin (x) \cos (y(x))=0 \] ✓ Mathematica : cpu = 0.150897 (sec), leaf count = 29
DSolve[Cos[y[x]]*Sin[x] + Cos[x]*Sin[y[x]]*Derivative[1][y][x] == 0,y[x],x]
\[\left \{\left \{y(x)\to -\cos ^{-1}\left (\frac {1}{2} c_1 \sec (x)\right )\right \},\left \{y(x)\to \cos ^{-1}\left (\frac {1}{2} c_1 \sec (x)\right )\right \}\right \}\] ✓ Maple : cpu = 0.09 (sec), leaf count = 11
dsolve(diff(y(x),x)*sin(y(x))*cos(x)+cos(y(x))*sin(x) = 0,y(x))
\[y \left (x \right ) = \arccos \left (\frac {c_{1}}{\cos \left (x \right )}\right )\]