Vestigial trigonometry functions
http://datagenetics.com/blog/march22017/index.html [datagenetics.com]
2017-03-09 05:38
There are, however, whole families of additional trig functions you might never have heard about. These include:
Versine, Vercosine, Coversine, Covercosine, Exsecant, Excosecant, Haversince, Havercosine, Hacoversine, Hacovercosine.