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kidnapper_ran


Giải hệ pt
[TEX] \left{sinx+cosx= \fr{\sqrt{2}}{2} \\ x-y= \frac{-\pi}{4}[/TEX]
[TEX] \left{sinx+cosx= \fr{\sqrt{2}}{2} \\ x-y= \frac{-\pi}{4}[/TEX]
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