$x=\pm\frac{\pi}{12}+k\ \frac{2\pi}{3}\left(k\in Z\right)$  

 $x=\pm\frac{\pi}{4}+k2\pi\left(k\in Z\right)$  

 $x=\pm\frac{\pi}{4}+\frac{k2\pi}{3}\left(k\in Z\right)$  

 $x=\pm\frac{9\pi}{4}+\frac{k2\pi}{3}\left(k\in Z\right)$  

 $x=\frac{\pi}{9}+\frac{k2\pi}{3}\left(k\in Z\right)$  hoặc  $x=\frac{5\pi}{9}+k2\pi\left(k\in Z\right)$  

 $x=\pm\frac{\pi}{18}+\frac{k2\pi}{3}\left(k\in Z\right)$  

 $x=\frac{\pi}{18}+\frac{k2\pi}{3}\left(k\in Z\right)$  hoặc  $x=\frac{5\pi}{18}+\frac{k2\pi}{3}\left(k\in Z\right)$  

 $x=-\frac{\pi}{18}+\frac{k2\pi}{3}\left(k\in Z\right)\ và\ \ x=\frac{7\pi}{18}+\frac{k2\pi}{3}\left(k\in Z\right)$  

 $x=\frac{-\pi}{2}+k2\pi,k\in Z$  

 $x=\frac{\pi}{2}+k2\pi,k\in Z$  

 $x=\frac{\pi}{2}+k\pi,k\in Z$  

 $x=k\pi,k\in Z$  

 $x=\frac{\pi}{6}+k2\pi,k\in Z$  

 $x=\frac{\pi}{6}+k2\pi,k\in Z;$  

 $x=-\frac{\pi}{6}+k2\pi,k\in Z$  

 $x=\frac{\pi}{6}+k2\pi;$  

 $x=\frac{-\pi}{6}+k2\pi,k\in Z$  

 $x=\frac{\pi}{2}+k\pi,k\in Z$  

 $x=\frac{\pi}{4}+\frac{k\pi}{2},k\in Z$  

 $x=\frac{\pi}{2}+k2\pi,k\in Z$  

 $x=k\pi,k\in Z$  

 $\sin x=\frac{1}{2}$  

 $\cos x=\frac{1}{2}$  

 $\sin x=\frac{\sqrt{3}}{2}$  

 $\cos x=\frac{\sqrt{3}}{2}$  

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Vô nghiệm

 $\sin x=-1.$  

 $\cos x=\frac{2}{3}.$  

 $\sin x=\sqrt{2}.$  

 $\sin x=\frac{\sqrt{3}}{2}.$