Let \(\displaystyle S=\left\{ x \in \left( -\frac{\pi}{2},\, \frac{\pi}{2} \right) : 9^{\,1-\tan^{2}x} + 9^{\,\tan^{2}x} = 10 \right\} \) and \( \beta =\displaystyle \sum\limits_{x\in S} \tan^{2}\!\left( \frac{x}{3} \right) \), then \( \dfrac{1}{6} (\beta - 14)^{2} \) is equal to: