Sets or returns the angle of the first slice in the pie or doughnut chart.

public int AngleOfFirstSlice{ get; set; }
Public Property AngleOfFirstSlice() As Integer

This defaults to 0 when creating a new series.
If this is set to a value less than 0, it will be set to 360 + (value % 360).
If this is set to a value greater than 360 it will be set to value % 360.
Note: if this is set to 360, it will still be 360.

For 3D pie charts this will have the same value as the ChartSettings3D.RotationAngle.
This property is linked for series in the same group. See SettingsPieDoughnut for more information on how linking works.
For Bar Of Pie and Pie of Pie series setting this will have no effect and it will always return 0.