Determine the integrating factor μ(x)\mu(x)μ(x) for y′+ytan(x)=cos(x)y' + y \tan(x) = \cos(x)y′+ytan(x)=cos(x).
cos(x)\cos(x)cos(x)
sec(x)\sec(x)sec(x)
sin(x)\sin(x)sin(x)
ecos(x)e^{\cos(x)}ecos(x)