Let $a \in \left(0, \dfrac{\pi}{2}\right)$ be fixed. If $\displaystyle \int \dfrac{\tan x + \tan a}{\tan x - \tan a} , dx = A(x)\cos 2a + B(x)\sin 2a + C,$ where $C$ is a constant of integration, then the functions $A(x)$ and $B(x)$ are respectively: