## Trigonometry (11th Edition) Clone

$y=\frac{2\pi}{3}$
RECALL: $y=\arccos{x} \longrightarrow \cos{y}=x$ Note that: $\cos{(\frac{2\pi}{3})} = -\frac{1}{2}$ Thus, $y=\arccos{(-\frac{1}{2})}\longrightarrow y=\frac{2\pi}{3}$