/// <summary>
/// شیب خط
/// </summary>
/// <param name="l"></param>
/// <returns></returns>
public static Double slope(line l)
{
return((l.EndPoint.getY() - l.StartPoint.getY()) / (l.EndPoint.getX() - l.StartPoint.getX()));
}
/// <summary>
/// طول خط
/// </summary>
/// <param name="l"></param>
/// <returns></returns>
public static Double lengh(line l)
{
return(point.distance(l.StartPoint, l.EndPoint));
}