Public Function Speichenlänge(ByVal r1 As Double, ByVal r2 As Double, _
                                  ByVal w As Double, _
                                  ByVal adk As Double, _
                                  ByVal ads As Double) As Double
 
        Dim beta As Double = 2.0 * Math.PI * (adk / ads)
        Dim L2 As Double = _
           r1 * r1 + r2 * r2 + w * w - 2 * r1 * r2 * Math.Cos(beta)
 
        If L2 <= 0 Then Return -1
        Return Math.Sqrt(L2)
    End Function

Dim l As Double = Speichenlänge(590 / 2, 40 / 2, 71.6, 3, 36)