点导直线的距离

// 已知三点的坐标：
float Ax,Bx,Cx,Ay,By,Cy;
求C 到AB直线的距离.

L = sqrt( (Bx-Ax)^2 + (By-Ay)^2 )；

s = ((Ay-Cy)(Bx-Ax)-(Ax-Cx)(By-Ay)) / (L * L);

距离：
distance= fabs(s) * L;

若A，B点重合，两点迭在一起，L=0, 距离:
distance= sqrt( (Cx-Ax)^2 + (Cy-Ay)^2 )；

public class Distance
{
public static void main(String[] args)
{
Scanner input = new Scanner(System.in);
System.out.println("Please input the coordinates of the first point");
double aX = input.nextDouble();
double aY = input.nextDouble();
System.out.println("Please input the coordinates of the second point");
double bX = input.nextDouble();
double bY = input.nextDouble();
System.out.println("Please input the coordinates of the third point");
double cX = input.nextDouble();
double cY = input.nextDouble();

double ac = Math.sqrt((aY - cY) *