ArcGIS 點到直線的距離

/****點到直線的距離***
 * 過點（x1,y1）和點（x2,y2）的直線方程為：KX -Y + (x2y1 - x1y2)/(x2-x1) = 0
 * 設直線斜率為K = (y2-y1)/(x2-x1),C=(x2y1 - x1y2)/(x2-x1)
 * 點P(x0,y0)到直線AX + BY +C =0DE 距離為：d=|Ax0 + By0 + C|/sqrt(A*A + B*B)
 * 點（x3,y3）到經過點（x1,y1）和點（x2,y2）的直線的最短距離為：
 * distance = |K*x3 - y3 + C|/sqrt(K*K + 1)
 */
public static double GetMinDistance(IPoint pt1, IPoint pt2, IPoint pt3)
{
   double dis = 0;
   if (pt1.X == pt2.X){
    dis = Math.Abs(pt3.X - pt1.X);
        return dis;
   }
   double lineK = (pt2.Y - pt1.Y) / (pt2.X - pt1.X);
   double lineC = (pt2.X * pt1.Y - pt1.X * pt2.Y) / (pt2.X - pt1.X);
   dis = Math.Abs(lineK * pt3.X - pt3.Y + lineC) / (Math.Sqrt(lineK * lineK + 1));
   return dis;
}