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

namespace лаба3на_отгруз
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        public double Skrug(double r1)
        {
            double p = 3.1416;
            return p * Math.Pow(r1, 2.0);

        }

        private void button1_Click(object sender, EventArgs e)
        {
            double r1, r2, S;
            r1 = Convert.ToDouble(textBox1.Text);
            r2 = Convert.ToDouble(textBox2.Text);
            S = Skrug(r2) - Skrug(r1);
            textBox3.Text = Convert.ToString(S);
        }

        private void button2_Click(object sender, EventArgs e)
        {
            Close();
        }
    }
}