' benötigt:
' - 1 Form
' - 1 PictureBox
' - 1 HScrollbar
 
' globale Variablen
Public x_neu1 As Double
Public start1 As Double
Public ende1 As Double
Public x_neu2 As Double
Public start2 As Double
Public ende2 As Double
Private Sub Form_Load()
    HScroll1.Value = 70
End Sub
Private Sub HScroll1_Change()
    ' -----------------------------
    ' Starteinstellungen
    ' -----------------------------
    PI = 3.1415    
    SehneS = 100
    ' -----------------------------
    ' alte Linse löschen
    ' -----------------------------
    ' hier noch Code einfügen
 
 
 
    ' -----------------------------
    ' neue Linse zeichnen
    ' -----------------------------
    Radius = HScroll1.Value
    Winkel = (SehneS / (2 * Radius))
    Phi = 2 * Arkussinus(Winkel)
    start1 = Phi / 2
    start2 = PI + Phi / 2
    ende1 = 2 * PI - Phi / 2
    ende2 = PI - Phi / 2
    HoeheH = SehneS / 2 * Tan(Phi / 4)
    x1_neu = 0 + HoeheH - Radius
    x2_neu = 0 - HoeheH + Radius
    Picture1.Circle (x1_neu, 0), Radius, vbRed, ende1, start1
    Picture1.Circle (x2_neu, 0), Radius, vbRed, ende2, start2
End Sub
Public Function Arkussinus(ByVal wert As Double) As Double
    Arkussinus = Atn(wert / Sqr((-wert) * wert + 1))
End Function
Private Sub Form_Resize()
    Picture1.Scale (-100, 100)-(100, -100)
End Sub

Gru