OOP VOLUME TRAPESIUM Dengan VB Net

Public Class Form1
      Public Class trapesium
        Public tinggi As Single
        Public jari_jari As Single
        Const phi = 3.14

        Public Function Volume_trapesium() As Double
            Return 1 / 3 * phi * jari_jari * jari_jari * tinggi
        End Function
    End Class


    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Dim objtrapesium As New trapesium
        With objtrapesium
            .tinggi = TextBox8.Text
            .jari_jari = TextBox9.Text
            TextBox7.Text = .Volume_trapesium
        End With
    End Sub

End Class