I noticed the above functions actually use radians so I made some quick functions to convert the degree value entered into radians:
Private Function radians(N As Double) As Double
    
    radians = N * (Pi / 180)
    
End Function

and I called it like:

Private Sub BtnSin_Click()
    
   On Error Resume Next
   Calc = radians(Calc)
   Calc = "sin(" & Calc & ")"
    DoCalc
    
End Sub

Pi is set as a constant or you can create another function to calculate an estimate of pi like this:
Private Function Pi() As Double

    Pi = Atn(1) * 4
    
End Function

What can I say, I like to enter the degrees