giải phương trình
[tex]cos^{2}x - \sqrt{3}sin x . cos x = \frac{3}{2}[/tex]
[tex]1 + tan2x = \frac{1- sin 2x}{cos^{2}2x}[/tex]
[tex]1)pt\Leftrightarrow \frac{1+cos2x}{2}-\frac{\sqrt{3}}{2}sin2x=\frac{3}{2}\\\Leftrightarrow cos2x-\sqrt{3}sin2x=2\\\Leftrightarrow cos(2x+\frac{\pi}{3})=1\\\Leftrightarrow ...\\2)DKXD:...\\pt\Leftrightarrow 1+\frac{sin2x}{cos2x}=\frac{1-sin2x}{cos^22x}\\\Rightarrow cos^22x+sin2xcos2x=1-sin2x\\\Leftrightarrow (cos^22x-1)+(sin2xcos2x+sin2x)=0\\\Leftrightarrow (cos2x+1)(cos2x-1+sin2x)=0\\\Leftrightarrow ...[/tex]