\(\Leftrightarrow\sin\left(2x-20^o\right)=60^o\)
\(\Leftrightarrow\left[{}\begin{matrix}2x-20^o=60^o+k360^o\\2x=180^o-60^o+k360^o\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}2x=80^o+k360^o\\2x=140^o+k360^o\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=40^o+k180^o\\x=70^o+k180^o\end{matrix}\right.\left(k\in Z\right)\)
\(sin\left(2x-20^o\right)=\dfrac{\sqrt{3}}{2}\) \(\Leftrightarrow\) \(2x-20^o=60^o+k360^o\) và \(2x-20^o=120^o+k360^o\) \(\Leftrightarrow\) \(x=40^o+k180^o\) và \(x=70^o+k180^o\).