1, Pt $\Leftrightarrow sin(2x + \frac{\pi }{4})=sin3x$$\Leftrightarrow 2x + \frac{\pi }{4} =3x +k2\pi ; 2x+ \frac{\pi }{4} = \pi -3x +k2\pi $
$\Leftrightarrow x= \frac{\pi }{4} - k2\pi ; x=\frac{3\pi }{20} + \frac{k2\pi }{5} , k\in Z$
2, Pt $\Leftrightarrow cos (x- \frac{\pi }{3}) = -cos3x$
$\Leftrightarrow x - \frac{\pi }{3}=-3x +k2\pi ; x -\frac{\pi }{3} = 3x +k2\pi $
$\Leftrightarrow x= \frac{\pi }{12} +k\frac{\pi }{2} ; x= \frac{-\pi }{6} -k\pi , k \in Z$