public double calcAngleBetweenLines(Entry start1,Entry end1,Entry start2,Entry end2){
  double angle1=calcAngleWithRatios(start1,end1);
  double angle2=calcAngleWithRatios(start2,end2);
  return Math.abs(angle1 - angle2);
}

public double calcAngleBetweenLines ( Entry start1 , Entry end1 , Entry start2 , Entry end2 ) { double angle1 = calcAngleWithRatios ( start1 , end1 ) ; double angle2 = calcAngleWithRatios ( start2 , end2 ) ; return Math . abs ( angle1 - angle2 ) ; }
calculates the angle between two given lines . the provided entry objects mark the starting and end points of the lines .
