(e sin y-mx)y'=e cos y+my (e sin y-mx)dy=(e cos y+my)d e cos ydux-e sin ydy+myd+mody=0 d(e )cosy+e d(cos y)+m(ydx+xdy)=0 d(e cos y)+d(my)=0 d(e cos y+mxy)=0 GS. e cos y+ mxy=c( sin ) ( cos ) x x e y mx dy e y my dx    ( sin ) cos x x e y mx y e y my     cos sin 0 x x e ydx e ydy mydx mxdy     ( )cos (cos ) ( ) 0 x x d e y e d y m ydx xdy     ( cos ) ( ) 0 x d e y d mxy   ( cos ) 0 x d e y mxy   . cos . x    GS e y mxy C