Incorrect values are written to the text file - vb.net

Question

I want to write the values of a sine function to a text file. The function is
In my graphing calculator, I also have to add π if I want to plot the function in radians.
How do I have to write this in the source code? Wrong values come out every time, regardless of whether I insert or leave out π.
I would like to have a y-value of 0 for t = 0 to 14400, and also from t = 69060 onwards. In between, according to its formula, the sine function of y = 0 should rise, reach 8, and fall again (second zero as said at 69060).
Private Sub ButtonStart_Click(sender As Object, e As EventArgs) Handles ButtonStart.Click
Dim Path As String = ""
Using SFD As New CommonSaveFileDialog
SFD.Title = "Ordner, in dem die Textdatei gespeichert werden soll, auswählen"
SFD.Filters.Add(New CommonFileDialogFilter("Textdateien", ".txt"))
Dim di As New IO.DirectoryInfo(Application.StartupPath)
If di.Parent.Name = "bin" Then
di = di.Parent.Parent.Parent ' AnyCPU
ElseIf di.Parent.Parent.Name = "bin" Then
di = di.Parent.Parent.Parent.Parent ' x64, x86
End If
If System.IO.Directory.Exists(di.FullName) Then
SFD.InitialDirectory = di.FullName
Else
SFD.InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.Desktop)
End If
If SFD.ShowDialog() = CommonFileDialogResult.Ok Then
Path = SFD.FileName & ".txt"
Else
Return
End If
End Using
ButtonStart.BackColor = Color.FromArgb(255, 255, 0)
Application.DoEvents()
Using textfile As System.IO.StreamWriter = My.Computer.FileSystem.OpenTextFileWriter(Path, False, System.Text.Encoding.UTF8)
textfile.WriteLine($"Time{Tab}V(OUT)")
For t As UInt32 = 0UI To 86400UI Step 1UI
If t < 14400UI OrElse (t >= 14400UI AndAlso t <= 69060UI) Then
textfile.WriteLine(t.ToString(Eng).PadLeft(10, "0"c) & Tab & 0.0.ToString(Eng))
Else
Dim Value As Double = 8.0 * Math.Sin(1.0 * Math.PI / 54660.0 * t + 2.0 * Math.PI - 0.2634467618)
textfile.WriteLine(t.ToString(Eng).PadLeft(10, "0"c) & Tab & Value.ToString(Eng))
End If
Next
textfile.Close()
End Using
ButtonStart.BackColor = Color.FromArgb(0, 255, 0)
End Sub

Answer 1

This should be your function
Function f(t As Double) As Double
Dim amplitude = 8
Dim period = 54660
Dim phaseDegrees = 177
Dim phaseRadians = phaseDegrees * Math.PI / 180
Dim vertical = 0
Dim a = amplitude
Dim b = 2 * Math.PI / period
Dim c = phaseRadians
Dim d = vertical
Return a * Math.Sin(b * (t + c)) + d
End Function
See image, from https://www.mathsisfun.com/algebra/amplitude-period-frequency-phase-shift.html

Answer 2

I found a solution. It has to be
Amplitude * sin(2πf*t + phase in rad) + offset
Using textfile As System.IO.StreamWriter = My.Computer.FileSystem.OpenTextFileWriter(Path, False, System.Text.Encoding.UTF8)
For t As UInt32 = 0UI To 86400UI Step 1UI
If t < 14400UI OrElse (t > 69060UI AndAlso t <= 86400UI) Then
textfile.WriteLine(t.ToString(Eng).PadLeft(10, "0"c) & Tab & 0.0.ToString(Eng))
Else
Dim Value As Double = 4.0 * Math.Sin(2 * Math.PI * 1.0 / 54660.0 * t + 177.0 * Math.PI / 180.0) + 4.0
textfile.WriteLine(t.ToString(Eng).PadLeft(10, "0"c) & Tab & Value.ToString(Eng))
End If
Next
textfile.Close()
End Using