Maybe I just don't get the question, but it's asking for three functions of: cmath, cstring, and cstdlib. For example, in cmath, I chose Trigonometric, Hyperbolic, and Exponential and Logarithmic Functions. What would the signature be of these? Just need to be put on the right path. Thanks!
Trigonometric, Hyperbolic, and Exponential and Logarithmic are not actually functions. It is just a way to categorize the many functions offered by cmath.
If you type "cmath" into the Search bar at the top of the page, you will be taken to this site's reference page for the cmath library. It will list all the functions offered by the library. Pick one, say, "cos". Click the link to "cos" and it will take you to the reference for that function. At the very top, you'll see a line that looks like this: double cos (double x); That is the function signature for "cos".
Sounds like you need to do this for three functions from each of cmath, cstring, and cstdlib for a total of 9 signatures.