x y'(x) \left(y(x) \sin \left(\frac{y(x)}{x}\right)-x \cos \left(\frac{y(x)}{x}\right)\right)-y(x) \left(y(x) \sin \left(\frac{y(x)}{x}\right)+x \cos \left(\frac{y(x)}{x}\right)\right)=0