hi

i'm trying to find the domain of this function :

let $\displaystyle \mathbb{E} = [-\pi,+\pi]$

$\displaystyle x \in \mathbb{E} ; $ $\displaystyle f(x) = \sqrt{\frac{1+\cos \left ( x \right )}{1-\cos \left ( x \right )}}$

i started by this :

$\displaystyle D = \left \{ x\in \mathbb{E}\mid 1-cos(x)\neq 0 , \frac{1+cos(x)}{1-cos(x)}\geq 0 \right \} $

which means $\displaystyle 1-cos(x) > 0$ and $\displaystyle 1+cos(x) \geq 0$ because we have $\displaystyle -1\leq cos(x)\leq 1$

what should i do next ?

thanks a lot