In Google Sheets, IMSIN is a function that returns the sine of a complex number in the form of "x + yi".

The IMSIN function takes one argument, which is the complex number in the format of "x + yi", where x and y are real numbers and i is the imaginary unit. The function returns the sine of the complex number.

Here's the syntax for the IMSIN function:

=IMSIN(complex_number)

For example, if you have a complex number of 2 + 3i, you can use the IMSIN function to calculate its sine as follows:

=IMSIN("2+3i")

This will return the sine of the complex number as a complex value.