[Toán 11] Lượng giác

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lovelycat_handoi95

nhiemlata1995 said:
a chi nao giai gium em bai nay voi : 2(cot2x-cot3x)=tan2x+cot3x em xin cam on :confused::confused::confused::confused::confused::confused:
Bấm để xem đầy đủ nội dung ...
ĐK: [TEX]sin4x\neq 0,sin3x\neq 0[/TEX]
[TEX]PT \Leftrightarrow 2\frac{sin3xcos2x-sin2xcos3x}{sin3xsin2x}=\frac{sin2xsin3x+cos2xcos3x}{sin3xcos2x}[/TEX]
[TEX]\Leftrightarrow 2sinxcos2x=cosxsin2x\Leftrightarrow 2tanx=tan2x=\frac{2tanx}{1-tan^2x}[/TEX]
[TEX]\Leftrightarrow tanx=0\Rightarrow PTVN[/TEX]

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