Справка LibreOffice 7.6

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

МНИМ.TAN(КомплексноеЧисло)

Complex_number is a complex number whose tangent 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.

=МНИМ.TAN("4-3i")

возвращает 0,00490825806749606-1,00070953606723i.

=IMTAN(2)

returns -2.18503986326152 as a string. The imaginary part is equal to zero, so it is not displayed in the result.