Make an appropriate substitution to find a solution of the equation dy/dx=sin(x-y). Does this general solution contain the linear solution y(x)=x-pi/2 that is readily verified by substitution in the differential equation? Here's what I did: v=x-y y=x-v y'=1-dv/dx 1-dv/dx=sin(v) 1-sin(v)=dv/dx dx=dv/(1-sin(v)) x=2/(cot(v/2)-1) The solution in the back of the book gives: x=tan(x-y) + sec(x-y) What am I doing wrong? Any help is greatly appreciated. Thanks!