ta có : \(sinB.cosB=\frac{\sqrt{3}}{4}\Leftrightarrow sin2B=\frac{\sqrt{3}}{2}\)
\(\Rightarrow\left[{}\begin{matrix}2B=\frac{\pi}{3}+k2\pi\\2B=\frac{2\pi}{3}+k2\pi\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}B=\frac{\pi}{6}+k\pi\\B=\frac{\pi}{3}+k\pi\end{matrix}\right.\) vậy ...