Problem

0 \le x \le 2\pi

and

|\cos x| \le \sin x

, then a. the set of all values of

x

\left[ \frac{\pi}{4}, \frac{3\pi}{4} \right]

b. the number of solutions that are integral multiple of

\frac{\pi}{4}

is four c. the sum of the largest and the smallest solution is

\pi

d. the set of all values of

x

x \in \left[ \frac{\pi}{4}, \frac{\pi}{2} \right) \cup \left( \frac{\pi}{2}, \frac{3\pi}{4} \right]