I have no recollection if this version was replied to the visitor.
Maybe not because all those magnitudes/unit ... make me double-sick !
This version as is from limbo left over.
The final InverseFunction is done wrt the two segments,
thus a bit + accurate and of simplified expression.

Solve Horrible maths [Inverse ill Posed Difficult].sm (75 KiB) downloaded 81 time(s).