I dont know the syntax for VBA but it do know a little C++ and C#,  I think you just need a simple conditional statement like:  If (shapevalue == 1) then (Area = length of side 1 * lenght of side 2)  Else (shapevalue==2) then (Area = ...  then after the conditional statements, use whatever function displays the value like Display.Area cout>>"Area =">>Area or something