// Programmer: Janet Joy
// A function to find the area of a circle
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

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

        private void btnSubmit_Click(object sender, EventArgs e)
        {
            // Get the radius by parsing the value in text box.
            string s = txtRadius.Text;
            double radius = 0;
            Double.TryParse(s, out radius);
            // Display the area of the circle by calling the function.
            lblArea.Text = areaCircle(radius).ToString();
        }
        private double areaCircle(double r)
        {
            // Calculate the area of a circel when passed the radius.
            return Math.PI * r * r;
        }
    }
}