Solution of the differential equation is \(\frac{{dy}}{{dx}} = \sin \left( {x + y} \right) + \cos \left( {x + y} \right)\)
1
\(x = \ln \left( {1 + \tan \frac{1}{2}\left( {x + y} \right)} \right) + c\)
2
\(x = ln (tan (x + y)) + c\)
3
\(x = ln (x + y + c)\)
4
\(x = tan (x + y + 1) + c\)