\[ y'(x)=(y(x)+\cos (x))^2+\sin (x) \] ✓ Mathematica : cpu = 0.110306 (sec), leaf count = 18
DSolve[Derivative[1][y][x] == Sin[x] + (Cos[x] + y[x])^2,y[x],x]
\[\left \{\left \{y(x)\to -\cos (x)+\frac {1}{-x+c_1}\right \}\right \}\] ✓ Maple : cpu = 0.078 (sec), leaf count = 16
dsolve(diff(y(x),x) = (y(x)+cos(x))^2+sin(x),y(x))
\[y \left (x \right ) = -\cos \left (x \right )+\frac {1}{-x +c_{1}}\]