## Precalculus (6th Edition) Blitzer

1 + $tan^{2}x$ = $sec^{2}x$ for all x $sec^{2}x$ - $tan^{2}x$ = 1. So for x = $\frac{\pi}{3}$, $sec^{2}\frac{\pi}{3}$ - $tan^{2}\frac{\pi}{3}$ = 1.