Parallelogram in TurboCAD Pro 7.1 - Ty Harness

I wrote this macro to answer a question in the Yahoo TurboCAD users forum, simply draw a parallelogram knowing the side lengths and a diagonal. The cosine rule sprang to mind and it's only a 5min job to write a simple macro like this. I think it'll be limited use for anyone else but it is a nice example of applying the cosine rule to a problem.

The macro (tcm) code can be downloaded from the Yahoo TurboCAD users forum.

Form Code


Private Sub calculatefromabc()

On Error GoTo eh


Dim a As Double, b As Double, c As Double
Dim X As Double, AngA As Double

Dim w As Double, h As Double

a = CDbl(aTextBox.Text)
b = CDbl(bTextBox.Text)
c = CDbl(cTextBox.Text)

X = (-a * a + b * b + c * c) / (2 * b * c)
AngA = Atn(-X / Sqr(-X * X + 1)) + 2 * Atn(1) 'arccosine

h = b * Sin(AngA)
w = b * Cos(AngA)

hTextBox.Text = CStr(h)
wTextBox.Text = CStr(w)

Label6.Caption = "-"



Exit Sub

eh:


Label6.Caption = "Error"
wTextBox.Text = ""
hTextBox.Text = ""


End Sub



Private Sub drawParallelogram(c As Double, w As Double, h As Double)


ActiveDrawing.Graphics.AddLineSingle 0, 0, 0, c, 0, 0 'base line c

ActiveDrawing.Graphics.AddLineSingle 0, 0, 0, w, h, 0 'diag line b
ActiveDrawing.Graphics.AddLineSingle c, 0, 0, w, h, 0 'line a
ActiveDrawing.Graphics.AddLineSingle w, h, 0, w - c, h, 0 'paralell c
ActiveDrawing.Graphics.AddLineSingle 0, 0, 0, w - c, h, 0 ' paralell a


End Sub


Private Sub aTextBox_Change()
calculatefromabc
End Sub

Private Sub bTextBox_Change()
calculatefromabc
End Sub


Private Sub CommandButton1_Click()

On Error GoTo eh:

Dim a As Double, c As Double

Dim w As Double, h As Double
c = CDbl(cTextBox.Text)
w = CDbl(wTextBox.Text)
h = CDbl(hTextBox.Text)


drawParallelogram c, w, h


Exit Sub

eh:
Label6.Caption = "Cannot draw parallelogram"


End Sub

Private Sub CommandButton2_Click()
Unload Me
End Sub


Private Sub cTextBox_Change()
calculatefromabc
End Sub




Private Sub UserForm_Click()


End Sub

Private Sub UserForm_Initialize()
calculatefromabc
End Sub

Module Code


Sub tydrawparallel()

frmparallel.Show

End Sub

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