`#yvy.`

`sin(x)=-1/2`

`<=>` `sin(x)=sin((-\pi)/(6))`

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

`<=>` $\left[\begin{matrix} x=\dfrac{-\pi}{6}+k2\pi\\ x=\dfrac{7\pi}{6}+k2\pi\end{matrix}\right.$

Vậy pt có tập no `S={(-\pi)/(6)+k2\pi ; (7\pi)/(6)+k2\pi ; kinZZ}`

 ${\color{blue}{\text {♡ iu vợ Yến Vy nhắm :c}}}$