Calculus: Early Transcendentals 8th Edition

$\frac{\pi}{3},\frac{2\pi}{3},\frac{4 \pi}{3}\frac{5 \pi}{3}$
We need to find the range for $x$ for the equation $3cot^{2}x=1$ $cot^{2}x=\frac{1}{3}$ or $tan^{2}x=3$ gives $tanx=±\sqrt 3$ This is true for x=$\frac{\pi}{3},\frac{2\pi}{3},\frac{4 \pi}{3}\frac{5 \pi}{3}$