The vercosine, written and also known as the "versed cosine," is a littleused trigonometric function defined by
(1)
 
(2)

where is the cosine.
The vercosine, written and also known as the "versed cosine," is a littleused trigonometric function defined by
(1)
 
(2)

where is the cosine.
Weisstein, Eric W. "Vercosine." From MathWorldA Wolfram Web Resource. https://mathworld.wolfram.com/Vercosine.html