<|system|>
Compute $\arccos (\cos 7).$  All functions are in radians.</s>.
<|user|>
Can you answer based on context?
<|assistant|>
Since $\cos (7 - 2 \pi) = \cos 7$ and $0 \le 7 - 2 \pi \le \pi,$ $\arccos (\cos 7) = 7 - 2 \pi.$