Справка LibreOffice 24.8

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

МНИМ.COS(КомплексноеЧисло)

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

A complex number is a string expression resulting in the form "a+bi" or "a+bj", where a and b are numbers.

If the complex number is actually a real number (b=0), then it can be either a string expression or a number value.

The function always returns a string representing a complex number.

If the result is a complex number with one of its parts (a or b) equal to zero, that part is not displayed.

=IMCOS("4-3i")

returns -6.58066304055116-7.58155274274654i.

=IMCOS(2)

returns -0.416146836547142 as a string. The imaginary part is equal to zero, so it is not displayed in the result.