AreaOfCircleinCS

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 _2022032301_CS_Area_Of_Circle
{
    public partial class frmArea : Form
    {
        public frmArea()
        {
            InitializeComponent();
        }

        private void btnHello_Click(object sender, EventArgs e)
        {
            MessageBox.Show("Hello World");
        }

        private void btnExit_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }

        private void btnCalculate_Click(object sender, EventArgs e)
        {
            float fA;
            float fR = float.Parse (txtR.Text);
            fA = 3.14f * fR * fR;
            txtA .Text = fA.ToString();
        }
    }
}