Option Strict On
Public Class Triangle
    Inherits Shape
    Private side1, side2, side3 As Double

    Sub New(ByVal sideA As Double, ByVal sideB As Double, ByVal sideC As Double)
        MyBase.New()
        side1 = sideA
        side2 = sideB
        side3 = sideC
    End Sub

    Sub New()

    End Sub

    Property SideA() As Double
        Get
            SideA = side1
        End Get
        Set(ByVal Value As Double)
            side1 = Value
        End Set
    End Property

    Property SideB() As Double
        Get
            SideB = side2
        End Get
        Set(ByVal Value As Double)
            side2 = Value
        End Set
    End Property

    Public Property SideC() As Double
        Get
            SideC = side3
        End Get
        Set(ByVal Value As Double)
            side3 = Value
        End Set
    End Property

    Public Overrides Function Area() As Double
        Dim Perim As Double
        Perim = Perimeter()
        Return (Math.Sqrt(Perim * (Perim - side1) * (Perim - side2) * (Perim - side3)))
    End Function

    Public Overrides Function Perimeter() As Double
        Return (side1 + side2 + side3)
    End Function

End Class

Public Class Circle
    Inherits Shape
    Private cRadius As Double

    Sub New(ByVal radius As Double)
        MyBase.New()
        cRadius = radius
    End Sub

    Sub New()

    End Sub

    Public Property Radius() As Double
        Get
            Radius = cRadius
        End Get
        Set(ByVal Value As Double)
            cRadius = Value
        End Set
    End Property

    Public Overrides Function Area() As Double
        Return (Math.PI * cRadius ^ 2)
    End Function

    Public Overrides Function Perimeter() As Double
        Return (2 * Math.PI * cRadius)
    End Function
End Class

Public Class Square
    Inherits Shape
    Private sSide As Double

    Sub New(ByVal Side As Double)
        MyBase.New()
        sSide = Side
    End Sub

    Sub New()

    End Sub

    Public Property Side() As Double
        Get
            Side = sSide
        End Get
        Set(ByVal Value As Double)
            sSide = Value
        End Set
    End Property

    Public Overrides Function Area() As Double
        Area = sSide * sSide
    End Function

    Public Overrides Function Perimeter() As Double
        Return (4 * sSide)
    End Function
End Class