Drawing to line segments and calculating intersection between them C#

Question

Hi i would like to know how can i get points from the second line i draw. Here is my code, for now i can draw lines with mouse event and draw lines with a button where i write the coordinates of the points. public partial class Form1 : Form { Graphics drawArea; private Point p1, p2; List p1List = new List(); List p2List = new List();

    public Form1()
    {
        InitializeComponent();
        drawArea = panel1.CreateGraphics();
    }

    private void panel1_Paint(object sender, PaintEventArgs e)
    {
        System.Drawing.Graphics graphicsObj;

        graphicsObj = CreateGraphics();

        Pen p = new Pen(System.Drawing.Color.Black, 1);

        for (int x = 0; x < p1List.Count; x++)
        {
            drawArea.DrawLine(p, p1List[x], p2List[x]);
        }
    }

    private void button1_Click(object sender, EventArgs e)
    {      
        p1.X = Convert.ToInt32(textBox1.Text);
        p1.Y = Convert.ToInt32(textBox3.Text);
        p2.X = Convert.ToInt32(textBox2.Text);
        p2.Y = Convert.ToInt32(textBox4.Text);

        Pen p = new Pen(System.Drawing.Color.Black, 2);
        drawArea.DrawLine(p, p1.X, p1.Y, p2.X, p2.Y);
    }

    void panel1_MouseDown(object sender, MouseEventArgs e)
    {
        if (p1.X == 0)
        {
            p1.X = e.X;
            p1.Y = e.Y;
        }
        else
        {
            p2.X = e.X;
            p2.Y = e.Y;

            p1List.Add(p1);
            p2List.Add(p2);

            panel1.Invalidate();
            p1.X = 0;
        }
    }
}

}