private void GetConicalFaceInfo(Face face)
{
    ConicalFace conicalFace = face as ConicalFace;
    if (null != conicalFace)
    {
       XYZ axis = conicalFace.Axis;
       XYZ origin = conicalFace.Origin;
        double halfAngle = conicalFace.HalfAngle;
        XYZ radius = conicalFace.get_Radius(0);
    }
}

Private Sub GetConicalFaceInfo(face As Face)
    Dim conicalFace As ConicalFace = TryCast(face, ConicalFace)
    If conicalFace IsNot Nothing Then
        Dim axis As XYZ = conicalFace.Axis
        Dim origin As XYZ = conicalFace.Origin
        Dim halfAngle As Double = conicalFace.HalfAngle
        Dim radius As XYZ = conicalFace.Radius(0)
    End If
End Sub