There is this problem:

If , express in terms ofa.

I expressed tan in terms of and isolated it. I obtained .

But what about the sign? For example, for the first period should be positive for values of x greater than 0 and negative for values of x less than 0, but there does not seem to be anything in the expression I obtained that can account for the sign. Could somebody tell me what I have done wrong?

Thanks a lot.