Let S={θ ∈(-2 π, 2 π): cos θ+1=√ 3 sin θ}. Then Σ_θ ∈ S θ is equal to:

Let $\displaystyle S=\{\theta \in(-2 \pi, 2 \pi): \cos \theta+1=\sqrt{3} \sin \theta\}$.Then $\displaystyle \sum_{\theta \in \mathrm{S}} \theta$ is equal to: