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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 11: giải phương trình sau: sin3x=cos2x

Toán Lớp 11: giải phương trình sau:
sin3x=cos2x

Comments ( 2 )

  1. Tập xác định: $D=R$
    $sin3x=cos2x$
    $⇔ sin3x=sin\Bigg(\dfrac{\pi}{2}-2x\Bigg)$
    $⇔ \left[ \begin{array}{l}3x=\dfrac{\pi}{2}-2x+k2\pi\\3x=\dfrac{\pi}{2}+2x+k2\pi\end{array} \right.$
    $⇔ \left[ \begin{array}{l}x=\dfrac{\pi}{5}+\dfrac{k2\pi}{5}\\x=\dfrac{\pi}{2}+k2\pi\end{array} \right.$ $(k∈Z)$
     

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222-9+11+12:2*14+14 = ? ( )

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