math 10 Secret Trig Functions Your Math Teachers Never Taught You David Ellis Dec 2, 2020 • 1 min read 10 Secret Trig Functions Your Math Teachers Never Taught YouHaversine? Exsecant? An introduction to obsolete trig functions and why we don’t use them anymoreScientific American Blog NetworkEvelyn LambExcerpt from https://blogs.scientificamerican.com/roots-of-unity/10-secret-trig-functions-your-math-teachers-never-taught-you/