procedure Circle2DGI2(x,y: Real; var Distance,Angle: Real);
begin
  Distance:=sqrt(x*x + y*y);
  y:= y * 1/Distance;
  if ( x >= 0 )
   then angle := Arccos(y) * 180 / Pi
   else angle := 180 + ArcCos(-y) * 180 / Pi;
end;