[toán11] lượng giác

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van99

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T

tranghh4

1)pt<=>[tex]sin^4 x-sin^2 xcos^2 x+cos^4 x=1-2sin^2 2x<=>1-\frac{3sin^2 2x}{4}=1-2sin^2 2x[/tex]---->tự giải.
 
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tranghh4

2)pt [tex]\Leftrightarrow cotx+sinx(\frac{cosxcos\frac{x}{2}+sinxsin\frac{x}{2}}{cosxcos\frac{x}{2}}=4 \Leftrightarrow cotx+tanx=4[/tex]---->tự giải.(ak phải có đk nưa nha)
 
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