The following VBA example creates a crescent by trimming one ellipse with another.
Sub Test()
Dim s1 As Shape, s2 As Shape
Set s1 = ActiveLayer.CreateEllipse(1.947283, 7.707756, 4.278425, 5.376614)
Set s2 = s1.Duplicate(0.560197, 0)
s2.Trim s1
s2.Delete
End Sub