The solution of differential equation xdx−ydyxdy−ydx=1+x2−y2x2−y2 is
x2−y2+x−y+C
x2−y2+x2+y2+C
x2−y2+1+x2−y2=cx+yx2−y2
x2−y2+1+x2−y2=cx−yx2+y2
Put x=rsecθ y=rtanθ⇒drsecθdθ=1+r2∫dr1+r2=∫secθdθlnr+1+r2=ln|secθ+tanθ|+ln|c|⇒x2−y2+1+x2−y2=∣c(x+y)x2−y2