A thorough look at the meaning and grammar of "reichen" and what "handing" has to do with "being enough" and "areas".
reichen, ausreichen, erreichen, der Bereich, hinreichend, ausreichend
The core idea of this root was:
stretching out, reaching out, stiffening
A good mental image is reaching out the arm.
It’s the origin of reach and reichen as well as the words rigor and rigid.
The verb gereichen
Does this mean something like:
bring in sufficient of something to have an effect?
That one is REALLY rare, and only used in a few combinations (Ruhm, Ehre, Nachteil, Vorteil).
The idea is something like “to add to X”.
No one would say that in daily life ever, though. It’s really one just for /from the books.