# Math Help - Trig problem

1. ## Trig problem

hi everyone
Assume that $\alpha ,\beta ,\gamma$ satisfy $0< \alpha < \beta < \gamma < 2\pi$ if,
$\cos(x+\alpha )+\cos(x+\beta )+\cos(x+\gamma )=0,\forall x \in \mathbb{R}$.
Find $\gamma -\alpha$
just hints
thanks.

2. If the relationship is true for all x, it's certainly true for x=-beta, x=-alpha and x=-gamma. Try substituting in these values and what you're looking for will fall out.