public double CrossProduct(Vector v)
{
return _x * v.Y - v.X * _y;
}
public static double DistancePointLine(PointF pt, PointF lnA, PointF lnB)
{
Vector v1 = new Vector(lnA, lnB);
Vector v2 = new Vector(lnA, pt);
v1 /= v1.Magnitude;
return Math.Abs(v2.CrossProduct(v1));
}