Machine Problem

Write a program that will ask the user to give a radius of a circle and the program will compute

the area of the circle.

Use the following formula below.

area = (3.14 * radius * radius)

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Program Listing

' Area of the Rectangle in VB.NET
' Prof. Jake Rodriguez Pomperada, MAED-IT, MIT
'  and
' Bacolod City, Negros Occidental Philippines
' May 16, 2021   Sunday  1:10 PM

Public Class Form1
    'Declaring constant value of PI of the circle
    Public Const PI = 3.14

    ' Compute Button
    Private Sub btnCompute_Click(sender As Object, e As EventArgs) Handles btnCompute.Click
        Dim radius As Single = 0.0F
        Dim area As Single = 0.0F
        Dim radius_value As String

        radius_value = txtRadius.Text

        If radius_value = "" Or IsNumeric(radius_value) = False Then
            MessageBox.Show("Please enter a radius value.")
            area = PI * Val(radius_value) * Val(radius_value)
            txtArea.Text = area.ToString("#####.##")
            txtArea.ReadOnly = True
        End If

    End Sub
    ' Clear Button
    Private Sub btnClear_Click(sender As Object, e As EventArgs) Handles btnClear.Click
        txtRadius.Text = ""
        txtArea.Text = ""
    End Sub

    Private Sub btnQuit_Click(sender As Object, e As EventArgs) Handles btnQuit.Click
        Dim result = MessageBox.Show(" Are you sure you want to quit the program?", "Confirmation", MessageBoxButtons.YesNo, MessageBoxIcon.Question)
        If result = DialogResult.Yes Then
            txtRadius.Text = ""
            txtArea.Text = ""
        End If
    End Sub
End Class