Заданы координаты трех вершин треугольника (x1,y1) (x2, y2) (x3, y3). найти его периметр и площадь. написать программу в vba

Sub PS()
    Dim x1 As Double, y1 As Double, x2 As Double, y2 As Double
    Dim x3 As Double, y3 As Double
    x1 = Cells(2, 2): y1 = Cells(2, 3)
    x2 = Cells(3, 2): y2 = Cells(3, 3)
    x3 = Cells(4, 2): y3 = Cells(4, 3)
    a = L(x1, y1, x2, y2)
    b = L(x2, y2, x3, y3)
    c = L(x3, y3, x1, y1)
    P = a + b + c
    Cells(6, 2) = P
    p2 = P / 2
    S = Sqr(p2 * (P - a) * (P - b) * (P - c))
    Cells(7, 2) = S
End Sub

Function L(x1 As Double, y1 As Double, x2 As Double, y2 As Double) As Double
    L = Sqr((x2 - x1) ^ 2 + (y2 - y1) ^ 2)
End Function