## Trigonometry (11th Edition) Clone

$\frac{3\pi}{4}$
RECALL: Since cosine and arccosine are inverse functions of each other, then, for all valid values of $x$, $\arccos{(\cos(x))}=x$ Thus, $\arccos{(\cos{(\frac{3\pi}{4})})}=\frac{3\pi}{4}$