Excel VBA

I've encoutered a weird value using excel VBA, attached below is the code. I found that whenever i tried to print AMBA, it gives me -3.014722032 whereas it should be 0.1268. the latter value can also be obtained if I change pi into 3.14 in      AMBA = Pi - AAMB - AMAB .... It's weird that if I change it back into pi, -3.014 is instead obtained. why is this?

Function TransportCalc(array1 As Range, xM, yM, zM, z$)
'--input Base Case data
     xA = WorksheetFunction.Index(array1, 1, 1)
     yA = WorksheetFunction.Index(array1, 1, 4)
     xB = WorksheetFunction.Index(array1, 2, 1)
     yB = WorksheetFunction.Index(array1, 2, 4)
     xc = WorksheetFunction.Index(array1, 3, 1)
     yc = WorksheetFunction.Index(array1, 3, 4)
     xD = WorksheetFunction.Index(array1, 4, 1)
     yD = WorksheetFunction.Index(array1, 4, 4)
'--Distance Between Hydraulic Points
     LAB = ((xA - xB) ^ 2 + (yA - yB) ^ 2) ^ (1 / 2)
     LBC = ((xB - xc) ^ 2 + (yB - yc) ^ 2) ^ (1 / 2)
     LCD = ((xc - xD) ^ 2 + (yc - yD) ^ 2) ^ (1 / 2)
     LDA = ((xD - xA) ^ 2 + (yD - yA) ^ 2) ^ (1 / 2)
'--Distance Between Hydraulic Points and COG M
     LMA = ((xA - xM) ^ 2 + (yA - yM) ^ 2) ^ (1 / 2)
     LMB = ((xB - xM) ^ 2 + (yB - yM) ^ 2) ^ (1 / 2)
     LMC = ((xc - xM) ^ 2 + (yc - yM) ^ 2) ^ (1 / 2)
     LMD = ((xD - xM) ^ 2 + (yD - yM) ^ 2) ^ (1 / 2)
'--Angle calc, ccw naming
     AMAB = WorksheetFunction.Acos((LMA ^ 2 + LAB ^ 2 - LMB ^ 2) / (2 * LMA * LAB))
     AMBC = WorksheetFunction.Acos((LMB ^ 2 + LBC ^ 2 - LMC ^ 2) / (2 * LMB * LBC))
     AMCD = WorksheetFunction.Acos((LMC ^ 2 + LCD ^ 2 - LMD ^ 2) / (2 * LMC * LCD))
     AMDA = WorksheetFunction.Acos((LMD ^ 2 + LDA ^ 2 - LMA ^ 2) / (2 * LMD * LDA))
'--Tipping Length
     T_AB = LMA * Sin(AMAB)
     T_BC = LMB * Sin(AMBC)
     T_CD = LMC * Sin(AMCD)
     T_DA = LMD * Sin(AMDA)
'--Initiate Axle Load Calc
     AP = Cos(AMA) * LMA
     BQ = Cos(AMB) * LMB
     CR = Cos(AMC) * LMC
     DS = Cos(AMD) * LMD
'--AB shall be the line datum to draw the first perpendicular line from COG M
     AAMB = WorksheetFunction.Acos((LMA ^ 2 + LMB ^ 2 - LAB ^ 2) / (2 * LMA * LMB))
     AMBA = Pi - AAMB - AMAB
     APMB = Pi - AMBA - Pi / 2
'--Tipping Length
     Select Case (z$)
     Case "TAB": TransportCalc = T_AB
     Case "TBC": TransportCalc = T_BC
     Case "TCD": TransportCalc = T_CD
     Case "TDA": TransportCalc = T_DA
     Case "AAMB": TransportCalc = AAMB
     Case "AMAB": TransportCalc = AMAB
     Case "AMBA": TransportCalc = AMBA
     End Select
End Function
'---