PT\(\Leftrightarrow cos2x-\sqrt{3}sin2x=-\sqrt{3}\)
\(\Leftrightarrow\dfrac{1}{2}cos2x-\dfrac{\sqrt{3}}{2}sin2x=-\dfrac{\sqrt{3}}{2}\)
\(\Leftrightarrow cos\left(2x+\dfrac{\pi}{3}\right)=-\dfrac{\sqrt{3}}{2}\)
\(\Leftrightarrow\left[{}\begin{matrix}2x+\dfrac{\pi}{3}=\dfrac{5\pi}{6}+k2\pi\\2x+\dfrac{\pi}{2}=-\dfrac{5\pi}{6}+k2\pi\end{matrix}\right.\)(\(k\in Z\))\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{\pi}{4}+k\pi\\x=-\dfrac{2\pi}{3}+k\pi\end{matrix}\right.\)\(\left(k\in Z\right)\)
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