- Sử dụng công thức nhân, hạ bậc trong giải phương...

A $x= \frac{\Pi }{3}+\frac{k\Pi }{3} ;x= \frac{\Pi }{4}+\frac{k\Pi }{2}$

B $x= \frac{\Pi }{6}+\frac{k\Pi }{3} ;x= \frac{\Pi }{4}+k\Pi$

C $x= \frac{\Pi }{6}+\frac{k\Pi }{3} ;x= \frac{\Pi }{4}+\frac{k\Pi }{2}$

D $x= \frac{\Pi }{2}+\frac{k\Pi }{2} ;x= \frac{\Pi }{4}+\frac{k\Pi }{2}$

A $x = k\pi $

B $x =6 k\pi $

C $x = {{k\pi } \over 2}$

D $x = {\pi \over 4} + k2\pi $

A $x = \frac{\pi }{4} + k\pi;\,\,x = - \frac{\pi }{2} + k2\pi ;\,\,x = \frac{{2k\pi }}{3}\,\,\left( {k \in Z} \right)$

B $x = \frac{\pi }{4} + k\pi ;\,\,x = \frac{\pi }{2} + k\pi ;\,\,x = \frac{{2k\pi }}{3}\,\,\left( {k \in Z} \right)$

C $x = \frac{\pi }{3} + k\pi ;\,\,x = - \frac{\pi }{2} + k2\pi ;\,\,x = - \frac{{2k\pi }}{3}\,\,\left( {k \in Z} \right)$

D $x = \frac{\pi }{6} + k\pi ;\,\,x = - \frac{\pi }{2} + k\pi ;\,\,x = \frac{{2k\pi }}{3}\,\,\left( {k \in Z} \right)$