1. The smallest positive period of the function $f(x)=|\sin 2 x+\cos 2 x|$ is
A. $2 \pi$
B. $\pi$
C. $\frac{\pi}{2}$
D. $\frac{\pi}{4}$
Solve:
$f(x)=\left|\sqrt{2} \sin \left(2 x+\frac{\pi}{4}\right)\right| \Rightarrow T=\frac{\pi}{2}$, so choose $C$.

