Cho k, m, n ϵ Z, hãy thu gọn x:
a) \(\left[{}\begin{matrix}x=\frac{\pi}{2}+k\pi\\x=\frac{\pi}{6}+m\pi\\x=-\frac{\pi}{6}+n\pi\end{matrix}\right.\)
b) \(\left[{}\begin{matrix}x=\frac{\pi}{4}+k\pi\\x=-\frac{\pi}{4}+m\pi\\x=\frac{n\pi}{2}\end{matrix}\right.\)