用C#画圆

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

namespace sin
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Graphics DrawInterface = panel1.CreateGraphics();
            Pen MyPenBlue = new Pen(Color.Blue, 5);
            Pen MyPenBlack = new Pen(Color.Black, 5);
            Pen MyPenControl = new Pen(Color.FromName("Control"), 3);
            Pen MyPenRed = new Pen(Color.FromArgb(128, 255, 0, 0), 3);

            DrawInterface.DrawLine(MyPenBlack, 0, 300, 800, 300); //画直线
            int i;
            double angle1;
            float x1, y1, x2, y2;

             for (i = 0; i < 360; i+=30) //画圆
             {
                  angle1 = (float)i * 2 * 3.14 / 360;

                  x1 = (float)(300 - 200 * Math.Sin(angle1));
                  y1 = (float)(300 - 200 * Math.Cos(angle1));

                  DrawInterface.DrawEllipse(MyPenRed, x1, y1, 30, 30);
                  Thread.Sleep(20);
              }
        }
    }
}