Calculus 10th Edition

The equation of the tangent line is $y=2\sqrt{3}x+\dfrac{6-2\sqrt{3}\pi}{3}$.
$f'(x)=\dfrac{d}{dx}\sec{x}=\sec{x}\tan{x}$ $f'(\frac{\pi}{3})=(\sec{\frac{\pi}{3}})(tan{\frac{\pi}{3}})=2\sqrt{3}.$ Equation of tangent: $(y-y_0)=m(x-x_0)$ at point $(x_0, y_0)$ and slope $m$. $(y-2)=2\sqrt{3}(x-\frac{\pi}{3}) \rightarrow y=2\sqrt{3}x+\dfrac{6-2\sqrt{3}\pi}{3}$