I'm a beginner in CGA, taking it step by step by looking through old QnAs.
I haven't explored all of the CGA features yet, so there might be simpler and better codes, but assuming a rectangle, you can use the following code to bisect it diagonally.
diagonalAngle = atan(scope.sx/scope.sz)
Lot -->
rotateScope(0, diagonalAngle, 0) //You should rotateScope before split().
split(x){'.5:A.}