Calculating a distance between random points.

Question

Hi everyone,
so my situation is like this :
1) I have created a graph containing random points (3 different series). And the graph have three buttons .The first button will plot 30 random points on the chart. the second and third button will plot random point with different colour.
What I am trying to do now is I need to choose one random point from the 30 points, and calculate the distance from the chosen point to the qrand or qinit..
How can I do that? I really have no idea. Help!
public void ForBtn1()
Random qrand = new Random();
int[,] points = new int[100, 2];
int qinitx, qinity;
for (int i = 0; i < 30; i++)
int pointx = qrand.Next(0, 100);
int pointy = qrand.Next(0, 100);
points[i, 0] = pointx;
points[i, 1] = pointy;
qinitx = points[0,0];
qinity = points[0, 1];
chart1.Series["Initial Point"].Points.AddXY(pointx, pointy);
chart1.Series["Initial Location"].Points.AddXY(qinitx,qinity);
//To initialize random points and initial point
private void button1_Click(object sender, EventArgs e)
ForBtn1();
private void chart1_Click(object sender, EventArgs e)
//To initialize rand_config
private void button2_Click(object sender, EventArgs e)
Random qrand = new Random();
int[,] points = new int[100, 2];
int qrandx, qrandy;
qrandx = qrand.Next(0,100);
qrandy = qrand.Next(0,100);
chart1.Series["Random Configuration"].Points.AddXY(qrandx, qrandy);
private void button3_Click(object sender, EventArgs e)

Answer 1

i cannot attach the photo here .. i dont know why. but here's the photo . check this link.. i uploaded it to fb.. 
https://fbcdn-sphotos-e-a.akamaihd.net/hphotos-ak-xpa1/v/t1.0-9/11054299_811876005567689_3794441462666954824_n.jpg?oh=7c9576e4f1f9b2a7e2ac9cf744383051&oe=55AC5BD5&__gda__=1438193773_becbb041c6c51cfc4db4b38c2d18e7a2