I don't really get what the question is asking, but I think you have to differentiate? If so I can help but I'm not sure of what it's asking tbh.

Is that [cos(cos(x))] / sec(x) ? sec(x) = 1/cos(x) cos(cos(x))*cos(x) when x --> 0 , cos(x) --> 1 so, cos(cos(x))*cos(x) ---> cos(1).