Private Sub Треугольник(a As Single, b As Single, C As Single, p As Single, s As Single)
p = a + b + C
Pp = p / 2
s = Sqr(Pp * (Pp - a) * (Pp - b) * (Pp - C))
End Sub

Private Sub CmdClear_Click()
txtA.Text = ""
txtB.Text = ""
txtC.Text = ""
txtP.Text = ""
txtS.Text = ""
End Sub

Private Sub CmdOpen_Click()
Dim a As Single
Dim b As Single
Dim C As Single
Dim p As Single
Dim s As Single
a = Val(txtA.Text)
b = Val(txtB.Text)
C = Val(txtC.Text)
Call Треугольник(a, b, C, p, s)
txtP.Text = Str(p)
txtS.Text = Str(s)
End Sub