Private Sub Command1_Click()
a = Val(Text1.Text)
b = Val(Text2.Text)
c = Val(Text3.Text)
If ((a + b) > c) And ((a + c) > b) And ((b + c) > a) Then
Label5.Caption = "Треугольник"
Else
Label5.Caption = "Не треугольник"
End If
End Sub

Private Sub Command2_Click()
a = Val(Text1.Text)
b = Val(Text2.Text)
c = Val(Text3.Text)
If ((a + b) > c) And ((a + c) > b) And ((b + c) > a) Then
p = (a + b + c) / 2
Label5.Caption = Sqr(p * (p - a) * (p - b) * (p - c))
Else
Label5.Caption = "Не треугольник"
End If
End Sub

Private Sub Command3_Click()
a = Val(Text1.Text)
b = Val(Text2.Text)
c = Val(Text3.Text)
If ((a + b) > c) And ((a + c) > b) And ((b + c) > a) Then
Label5.Caption = Val(a + b + c)
Else
Label5.Caption = "Не треугольник"
End If
End Sub