a) \(y=\sin x=0\)
\(\Rightarrow x=k\pi,k\in\mathbb Z\)
Với \(-\pi\le k\pi\le 3\dfrac{\pi}{2}, k\in\mathbb Z\)
\(\Rightarrow -1\le k\le \dfrac{3}{2},k\in\mathbb Z\)
\(\Rightarrow k=\{-1; 0; 1\}\)
\(\Rightarrow x=\{0;\pm\pi\}\).
b) \(y=\sin x=1\)
\(\Rightarrow x=\dfrac{\pi}{2}+k2\pi,k\in\mathbb Z\)
Với \(-\pi\le \dfrac{\pi}{2}+k2\pi\le 3\dfrac{\pi}{2}, k\in\mathbb Z\)
\(\Rightarrow -\dfrac{3\pi}{2}\le k2\pi\le \pi\)
\(\Rightarrow -\dfrac{3}{4}\le k\le \dfrac{1}{2},k\in\mathbb Z\)
\(\Rightarrow k= 0\)
\(\Rightarrow x=\dfrac{\pi}{2}\).
