Справка LibreOffice 7.5

Returns the hyperbolic cosine of a complex number. The hyperbolic cosine of a complex number can be expressed by:

МНИМ.COSH(КомплексноеЧисло)

Complex_number is a complex number whose hyperbolic cosine is to be calculated.

=МНИМ.COSH("4-3i")

возвращает -27,0349456030742-3,85115333481178i.

=IMCOSH(2)

returns 3.76219569108363 as a string. The imaginary part is equal to zero, so it is not displayed in the result.