Đáp án:
Giải thích các bước giải:
`Cos (3x-pi/4)=sinx`
`⇔ cos (3x-pi/4)=cos (\frac{\pi}{2}-x)`
`⇔` \(\left[ \begin{array}{l}3x-\dfrac{\pi}{4}=\dfrac{\pi}{2}-x+k2\pi\ (k \in \mathbb{Z})\\3x-\dfrac{\pi}{4}=-\dfrac{\pi}{2}+x+k2\pi\ (k \in \mathbb{Z})\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}x=\dfrac{3}{16}\pi+\dfrac{k\pi}{2}\ (k \in \mathbb{Z})\\x=-\dfrac{\pi}{8}+k\pi\ (k \in \mathbb{Z})\end{array} \right.\)
