Points at infinity Algebraic extension to pts at infinity: introduction of homogeneous coordianted oo is not algebraic, only a symbol (x,yh if y*0, a finite pt if y=0, the pt at inf Rg the homogeneous coordinates are not unique, up to a scale11 Algebraic extension to pts at infinity: introduction of homogeneous coordiantes  is not algebraic, only a symbol if y 0, the pt at inf. ! ( , ) if 0, a finite pt = y  y x x y  Points at infinity: Rq: the homogeneous coordinates are not unique, up to a scale