if you mean what is the taylor expansion for tan(x) then evaluate it at a...well the one maclaurin expansion for three is $\displaystyle x+\frac{x^3}{3}+\frac{2x^5}{15}$
Well for example: $\displaystyle 1 + 2(x - \frac{1}{4}\;\pi) + 2(x - \frac{1}{4}\;\pi)^2 + ...$ is the answer in the book.
You wanted a taylor expansion CENTERED around $\displaystyle \frac{\pi}{4}$...haha ok thats different...here is what you do..use this $\displaystyle f(c)+f'(c)(x-c)+\frac{f''(c)(x-c)^2}{2!}$