L
lan_anh_a
Giúp em nhé ;
[TEX]3sin(x-\frac{\pi}{3})+4sin(x+\frac{\pi}{6})+5sin(5x+\frac{\pi}{6})=0[/TEX]
[TEX]3Sin(x - \frac{\pi }{3}) + 4Sin(x + \frac{\pi }{6}) + 5Sin(5x + \frac{\pi }{6}) = 0 \\ [/TEX]
đặt [tex]a = x - \frac{\pi }{3}[/tex]
thay vào dc
[TEX] 3Sina + 4Sin(x + \frac{\pi }{2}) + 5Sin(5x + \frac{\pi }{6}) = 0[/TEX]
[TEX]\Leftrightarrow3Sina + 4C{\rm{os}}a = 5Sin(5x + \frac{\pi }{6} + \pi ) [/TEX]
[TEX]\Leftrightarrow Sin(a + \alpha ) = Sin(5x + \frac{{7\pi }}{6}) [/TEX]
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