COSH (Number) COSH (Number) Number Number Number The input number. Returns Number Number The hyperbolic cosine. Details Returns the hyperbolic cosine of a number. The hyperbolic cosine is defined as ( EXP (Number) + EXP ( - Number)) / 2( EXP (Number) + EXP ( - Number)) / 2. The result is always greater than or equal to 1. The inverse of this function is ACOSH. Example COSH ( EXP (1)) COSH ( EXP (1)) Returns roughly 7.610.