The hyperbolic secant is the reciprocal of the hyperbolic sine.
Therefore, the value of the hyperbolic cosecant is given by the equation:
Further information is provided on the Wikipedia Hyperbolic Functions page.The Excel Csch function calculates the hyperbolic cosecant (csch) of a supplied angle.
Note: the Csch function was only introduced in Excel 2013 and so is not available in earlier versions of Excel.
The syntax of the function is:
Where the number argument is the angle (in radians) that you want to calculate the hyperbolic cosecant of. This must be between 2^27 and +2^27.
If the supplied number is equal to 0, the Csch function returns the #DIV/0! error.
Converting from Degrees to Radians
If your angle is in degrees, you will need to convert it into radians before supplying it to the Csch function. This can be done using the Excel Radians function:
The following spreadsheet shows three examples of the Excel Csch Function:
Formulas:
 Results:

Note that, in the examples above:
Further details and examples of the Excel Csch function are provided on the Microsoft Office website.
If you get an error from the Excel Csch function, this is likely to be one of the following:
#DIV/0!    Occurs if the supplied number is equal to 0. 
#NUM!    Occurs if the supplied number is less than 2^27 or is greater than 2^27. 
#VALUE!    Occurs if the supplied number argument is not recognized as a numeric value. 