Use mouse click to check the predefined points on the surface of the form to build lines between each pair of points

This is a kind of graphical test in which the subject has to find two lines using any four points in the rectangle to fit three geometric figures in the main figure. To make sure the subject hit exactly the dots, I built a circular surface around the points figured by distance 1,2,3 and 4. The goal is click with mouse on the points, and if four points are the good ones, two lines will be built between the pairs of points. If not, nothing. <pre>There seems to be a problem between checking distances d1, d2 / d3, d4 and MouseDown event. There are no errors, but the result is wrong, in the sense that I use "if ((distance1 <= 20 * 20) && (distance2 <= 20 * 20))" the line is not build when I press Drawing button, unless I use a single distance, distance1 or distance2, by clicking the mouse on any of the points 1 and 2. I don't see how I could add an image to be more explicit. <pre>Why 20 * 20? Square root of Distance1, for example, is a mathematical formula that describes the area of a circle with a radius of 20 pixels and its center defined by predefined coordinates that allows the user who mouse clicks on a point to be validated that he clicked correctly if he touches this area.
If you click the mouse exactly on point 1 defined by distance1, this means that distance1 <= 20 * 20, as well as in point 2, the program builds the first line between poin1 and point2.
Continuing to click with the mouse on point 3 defined by the distance3, as well as in point 4, the program builds the second line.
The code does not draw the line when I press point 1 and 2, 3 and 4 consecutively, but identifies correctly all the points because I checked them one by one separately.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsAppFG
{
    public partial class FormProbaFGpag1 : Form
    {
        Timer t = new Timer();
        static public DateTime startTimeForm = default(DateTime);

        public int TickCounter = 0;

        public Point StartPoint, EndPoint;

        static public Int32 RezP1 = 0;  //daca pag1 este corect facuta
        static public double ScorP1 = 0; //scor obtinut, 0.5 sau 1
        static public Int32 Pag1Omise = 0;

        public Int32 posX = 0;  //coord citite mouse
        public Int32 posY = 0;


        public Point P1 { get; set; }
        public Point P2 { get; set; }
        public Point P3 { get; set; }
        public Point P4 { get; set; }

        public Point FormCoordinates { get; set; }

        public Int32 distance1 = 0;
        public Int32 distance2 = 0;
        public Int32 distance3 = 0;
        public Int32 distance4 = 0;




        public FormProbaFGpag1()
        {
            InitializeComponent();

            Graphics g = this.CreateGraphics();

            this.Cursor = new Cursor(Cursor.Current.Handle);
            this.MouseDown += new MouseEventHandler(this.FormProbaFGpag1_MouseDown);
        }

        private void FormProbaFGpag1_Load(object sender, EventArgs e)
        {
            //backcolor
            this.BackColor = Color.White;


            t.Tick += delegate
            {
                t.Stop();
                MessageBox.Show("Timpul a axpirat. Apăsați OK pentru a merge mai departe.");



                FormProbaFGpag2 probaFGpag2 = new FormProbaFGpag2();
                probaFGpag2.Show();
                this.Close();



            };
            t.Interval = (int)TimeSpan.FromMinutes(0.5).TotalMilliseconds;
            t.Start();

        }


        protected override void OnPaint(PaintEventArgs e)  //creez o functie pe care o pot incarca direct din form load
        {
            base.OnPaint(e);
            this.SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
            this.SetStyle(ControlStyles.UserPaint, true);
            this.SetStyle(ControlStyles.AllPaintingInWmPaint, true);

            e.Graphics.Clear(Color.White);
            e.Graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
            e.Graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;

            Pen p = new Pen(Color.Black, 2);  //2 este grosimea width
            Pen pL = new Pen(Color.Blue, 2);  //linie
            Pen pR = new Pen(Color.Red, 4);
            Pen pAt = new Pen(Color.Transparent, 10);  //punct linie culoare transparent

            p.Alignment = System.Drawing.Drawing2D.PenAlignment.Center;
            pL.Alignment = System.Drawing.Drawing2D.PenAlignment.Center;
            pR.Alignment = System.Drawing.Drawing2D.PenAlignment.Center;
            pAt.Alignment = System.Drawing.Drawing2D.PenAlignment.Center;

            Rectangle rect1 = new Rectangle();

            rect1.X = 100;
            rect1.Y = 100;
            rect1.Width = 300;
            rect1.Height = 300;

            e.Graphics.DrawRectangle(p, rect1);

            //e.Graphics.DrawEllipse(Pens.Red, x1, x2, wid, wid);

            for (Int32 i = 100; i <= 400; i = i + 30)
                for (Int32 j = 100; j <= 400; j = j + 30)
                {
                    e.Graphics.DrawEllipse(pR, i, j, 4, 4);
                }
            //g.DrawEllipse(pR, 150, 100, 4, 4);


            p.Dispose();
            pL.Dispose();
            pR.Dispose();
            pAt.Dispose();
            e.Graphics.Dispose();
            //this.Refresh();



        }



        private void FormProbaFGpag1_MouseDown(object sender, MouseEventArgs e)
        {
            
            FormProbaFGpag1.ActiveForm.PointToScreen(Point.Empty);
            FormCoordinates = FormProbaFGpag1.ActiveForm.PointToScreen(e.Location);
            posX = e.X;
            posY = e.Y;
            

            if (e.Button == System.Windows.Forms.MouseButtons.Right)
            {
                Point pt = Cursor.Position;
                StartPoint = pt;
                EndPoint = pt;
                ControlPaint.DrawReversibleLine(StartPoint, EndPoint, Color.Black);
            }
        }

        private void buttonDeseneaza_Click(object sender, EventArgs e)
        {
            double ScorP11 = 0;
            double ScorP12 = 0;

            Graphics g = this.CreateGraphics();

            Pen pAc = new Pen(Color.Red, 2);
            Pen pAt = new Pen(Color.Transparent, 10);  //punct linie culoare transparent

            P1 = new Point(250, 100);  //1
            P2 = new Point(100, 250);  //2
            P3 = new Point(400, 250);  //3
            P4 = new Point(250, 400);  //4

            distance1 = (((posX - 250) * (posX - 250)) + ((posY - 100) * (posY - 100)));
            distance2 = (((posX - 100) * (posX - 100)) + ((posY - 250) * (posY - 250)));
            distance3 = (((posX - 400) * (posX - 400)) + ((posY - 250) * (posY - 250)));
            distance4 = (((posX - 250) * (posX - 250)) + ((posY - 400) * (posY - 400)));

            if ((distance1 <= 20 * 20) && (distance2 <= 20 * 20))
            {
                pAt = pAc;
                g.DrawLine(pAt, 250, 100, 100, 250);  // se construiește linia între punctele p1 si p2 de culoare rosie
                ScorP11 = 0.5;
            } 
            else
            {
                ScorP11 = 0;
            }


            if ((distance3 <= 20 * 20) && (distance4 <= 20 * 20))
            {
                pAt = pAc;
                g.DrawLine(pAt, 400, 250, 250, 400);  // se construiește linia între punctele p1 si p2 de culoare rosie
                ScorP12 = 0.5;
            }
            else
            {
                ScorP12 = 0;
            }

            ScorP1 = ScorP11 + ScorP12;

            if (ScorP1 == 1) RezP1 = 1;
            else if (ScorP1 < 1) RezP1 = 0;

            pAc.Dispose();
            pAt.Dispose();
            g.Dispose();
        }

        private void FormProbaFGpag1_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button == System.Windows.Forms.MouseButtons.Right)
            {
                ControlPaint.DrawReversibleLine(StartPoint, EndPoint, Color.Black); // erase previous line
                EndPoint = Cursor.Position;
                ControlPaint.DrawReversibleLine(StartPoint, EndPoint, Color.Black); // draw new line
            }
        }

        private void FormProbaFGpag1_MouseUp(object sender, MouseEventArgs e)
        {
            /*
             Graphics g = this.CreateGraphics();
             Pen pAc = new Pen(Color.Red, 2);

             if (e.Button == System.Windows.Forms.MouseButtons.Right)
             {
                 ControlPaint.DrawReversibleLine(StartPoint, EndPoint, Color.Black); // erase previous line

                 // ... do something with StartPont and EndPoint in here ...

                 // possibly add them to a class level structure to use in the Paint() event to make it persistent?
                 g.DrawLine(pAc, StartPoint, EndPoint);
             }
             */
        }

        private void buttonPag2NextPage_Click(object sender, EventArgs e)
        {
            FormProbaFGpag2 probaFGpag2 = new FormProbaFGpag2();
            probaFGpag2.Show();
            t.Stop();
            this.Close();
        }
    }
}