I have this script that runs ok as lat long are not the same. When they are the same I get run time error 11 can't divide by zero. Is there a way to trap this error. Any help is appreciated. 

Private Function ACos(X As Double) As Double
ACos = Atn(-X / Sqr(-X * X + 1)) + 2 * Atn(1)
End Function

Sub CalculateDistance()
Application.ScreenUpdating = False
    Set ws1 = Sheets("Input_Data")
    Set ws2 = Sheets("Output")
    Set ws3 = Sheets("Process_Data")
    Set ws4 = Sheets("Start")
    Set ws5 = Sheets("dyn RN")
    Dim D As Single
    Dim L1 As Single
    Dim L2 As Single
    Dim G1 As Single
    Dim G2 As Single
    Dim Name1, Nam2 As String
    Dim k, i, Dist As Long
    Const pi = 3.1415926

    i = Range("A1").End(xlDown).Row
    
    For k = i To 2 Step -1
    Lat1 = Format(ThisWorkbook.Worksheets("Process_Data").Cells(k, 3))
    Long1 = Format(ThisWorkbook.Worksheets("Process_Data").Cells(k, 4))
    Lat2 = Format(ThisWorkbook.Worksheets("Process_Data").Cells(k, 5))
    Long2 = Format(ThisWorkbook.Worksheets("Process_Data").Cells(k, 6))
      
    '-------------------Match Source and Target----------------------------
    'If source and Target are equal then their distance is zero.
        Name1 = ws3.Cells(k, 1)
        Name2 = ws3.Cells(k, 2)
        If Left(Name1, 7) = Left(Name2, 7) Then
            ws3.Cells(k, 7) = 0
            GoTo line1
        Else
            L1 = (90 - Lat1) * (pi / 180)
            L2 = (90 - Lat2) * (pi / 180)
            G1 = Long1 * (pi / 180)
            G2 = Long2 * (pi / 180)

       End If

D = ACos((Cos(L1) * Cos(L2) + Sin(L1) * Sin(L2) * Cos(G1 - G2)))
Dist = D * 3963

ThisWorkbook.Worksheets("Process_Data").Cells(k, 7) = Format(Dist)
line1:
Next k

End Sub