Hi All,

I am having some issues with figuring angles between 2 lines.
linea.jpglines.jpg
Above are 2 images of where I am trying to find the angle. The first I get 5 degrees, the second one I get 60 degrees. They should be 85 degrees and 120 degrees. I am using this formula:
 Slope_A = (iData(iOne).Y - iData(iOne).y1) / (iData(iOne).X - iData(iOne).x1)
        Slope_B = (iData(iOne + 1).Y - iData(iOne + 1).y1) / (iData(iOne + 1).X - iData(iOne + 1).x1)
        Tangent_of_Angle = (Slope_B - Slope_A) / (1 + Slope_A * Slope_B)
Here is the iData class:
Public Class TLine
        Public X As Double
        Public Y As Double
        Public x1 As Double
        Public y1 As Double
        Public tLength As Double
        Public Property LineLength() As Double
            Get
                Return SettLength()
            End Get
            Set(ByVal value As Double)
                tLength = value
            End Set
        End Property
        Private Function SettLength()
            If X = x1 Then 'line is straight
                tLength = Math.Abs(Y - y1)
            ElseIf Y = y1 Then 'line is straight
                tLength = Math.Abs(X - x1)
            Else
                tLength = Math.Sqrt(Squared(Math.Abs(X - x1)) + Squared(Math.Abs(Y - y1)))
            End If
            SettLength = tLength
        End Function
    End Class
I will post whatever information you need to help.
The data is coming from a drawing that is to scale so the data is correct.

Thanks for looking.
Any help at all is appreciated.