Giải phương trình sinx=1/2

`sinx=1/2`

`<=>sinx=sin`` \pi/6`  

`<=>` \(\left[ \begin{array}{l}x=\dfrac{\pi}{6}+k2\pi\\x=\pi-\dfrac{\pi}{6}+k2\pi\end{array} \right.\) 

`<=>` \(\left[ \begin{array}{l}x=\dfrac{\pi}{6}+k2\pi\\x=\dfrac{5\pi}{6}+k2\pi\end{array} \right.\) `(k∈Z)`

Vậy `S={\frac{\pi}{6}+k2\pi;\frac{5\pi}{6}+k2\pi | k∈Z}`