You can point to "sin", but in practice math just doesn't use multi-char variable names. The trig functions are special cases. Doesn't mean you're allowed to name arbitrary vars like that.
What about ker, coker, im, hom, end, aut, lim, colim, Set, Top, Man, Mat, Vect, GL, SL, SO, Lie, Gr, Tor, Ext, tr, Rep, char, rank, Isom, ann, hull, Diff, ...? I'm just copying multiletter names out of my preamble.tex file here.
I get that these aren't variables, but it's really not so uncommon outside of trigonometry to have multi-letter names for things that appear in equations.
I get that these aren't variables, but it's really not so uncommon outside of trigonometry to have multi-letter names for things that appear in equations.