Area Del Circulo En Visual Basic

Public Class Form1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim radio As Double, area As Double
radio = Val(TextBox1.Text)
area = Val(TextBox2.Text)
Const Pi As Double = 3.1416
radio = Val(TextBox1.Text)
area = radio * radio * Pi
TextBox2.Text = area
End Sub

Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
TextBox1.Text = " "
TextBox2.Text = " "
End Sub

Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
End
End Sub
End Class