

Secret Trig Functions Your Math Teachers Never Taught You - tokenadult
http://blogs.scientificamerican.com/roots-of-unity/2013/09/12/10-trig-functions-youve-never-heard-of/

======
chris_wot
It's interesting, I'm actually studying trigonometry at the moment. I have
found that the biggest gap is actually understanding what sine, cosine,
tangent, secant, cosecant and cotangent _are_. Once you realise they are lines
on a circle, and the reason for the names, things clicked into place for me!

