Toán Lớp 11: Giải hộ với ạ Vote 5* Sin(7x-π/3)=cos(5π/6-7x)

Question

Toán Lớp 11:  Giải hộ với ạ  Vote 5* Sin(7x-π/3)=cos(5π/6-7x)

annhocbichchaubich · Answer

~rai~        ( sin left(7x- dfrac{ pi}{3} right)= cos left( dfrac{5 pi}{6}-7x right)   Leftrightarrow  sin left(7x- dfrac{ pi}{3} right)= sin left( dfrac{ pi}{2}- dfrac{5 pi}{6}+7x right)   Leftrightarrow  sin left(7x- dfrac{ pi}{3} right)= sin left(7x- dfrac{ pi}{3} right) quad text{(lu&ocirc;n đ&uacute;ng)}   text{Vậy }S= mathbb{R}. )

doanthulan · Answer

$ begin{array}{l}  sin  left( {7x -  dfrac{ pi }{3}}  right) =  cos  left( { dfrac{{5 pi }}{6} - 7x}  right)     Leftrightarrow  sin  left( {7x -  dfrac{ pi }{3}}  right) =  cos  left( { dfrac{ pi }{2} -  left( {7x -  dfrac{ pi }{3}}  right)}  right)     Leftrightarrow  sin  left( {7x -  dfrac{ pi }{3}}  right) =  sin  left( {7x -  dfrac{ pi }{3}}  right)     Rightarrow 0 = 0     Rightarrow x  in  mathbb{R}  end{array}$