Its quite simple but im not sure of it basically:

Find the argument of

$\displaystyle 1 + itan(\frac{2pi}{3})$

So tan is

$\displaystyle \frac{sin}{cos}$

So i change tan to this and multiply through and get

$\displaystyle cos(\frac{2pi}{3}) + isin(\frac{2pi}{3})$

So i get the answer, the argument is 2pi / 3...seems pretty obvious...except its not...its -1pi / 3

:S, why is this?