@article {MATHEDUC.06310338,
author = {Li, Xiaoxue H.},
title = {Proof without words: monotonicity of $\tan x/x$ on $(0, \pi /2)$.},
year = {2013},
journal = {The College Mathematics Journal},
volume = {44},
number = {5},
issn = {0746-8342},
pages = {420-420},
publisher = {Mathematical Association of America (MAA), Washington, D.C.},
doi = {10.4169/college.math.j.44.5.420},
abstract = {Summary: A visual proof that $\tan x/x$ is monotonically increasing on $(0, \pi /2)$.},
msc2010 = {I20xx (G60xx)},
identifier = {2014e.00637},
}