`sin(2x+30^o)=1/2`
`⇔sin(2x+30^o)=sin(30^o)`
`⇔` $\left[\begin{matrix} 2x+30^o=30^o +k360^o\\ 2x+30^o=180^o -30^o +k360^o\end{matrix}\right.$
`⇔` $\left[\begin{matrix} 2x=-30^o+30^o +k360^o\\ 2x=-30^o +180^o -30^o +k360^o\end{matrix}\right.$
`⇔` $\left[\begin{matrix} 2x=k360^o\\ 2x=120^o +k360^o\end{matrix}\right.$
`⇔` $\left[\begin{matrix} x=k180^o\\ x=60^o+k180^o\end{matrix}\right.(k∈Z)$
$\text{Vậy phương trình có 2 họ nghiệm:}$
$\left[\begin{matrix} x=k180^o\\ x=60^o+k180^o\end{matrix}\right.(k∈Z)$
