Sh, ch are hyperbolic sine and cosine functions, and arch is anti-hyperbolic cosine function.

Hyperbolic functions are also divided into six types: hyperbolic sine, hyperbolic cosine, hyperbolic tangent, hyperbolic cotangent, hyperbolic secant and hyperbolic cotangent. Hyperbolic cosine function is one of them. Hyperbolic cosine function is written as cosh or abbreviated as ch. Hyperbolic sine function is written as sinh and abbreviated as sh.