Area and Perimeter of Circle

Public Class Form1
    Dim r, ar, per As Single
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Const PI As Single = 3.142
        r = TextBox1.Text
        ar = PI * r * r
        per = 2 * PI * r
        TextBox2.Text = ar
        TextBox3.Text = per

    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

    End Sub
End Class