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

Toán Lớp 11: giúp em với mn sin(3pi/4 – x) + cos(3x – pi/3) =0

Toán Lớp 11: giúp em với mn
sin(3pi/4 – x) + cos(3x – pi/3) =0

Comments ( 2 )

  1. Giải đáp + Lời giải và giải thích chi tiết:
      $sin(\dfrac{3\pi}{4}-x)+cos(3x-\dfrac{\pi}{3})=0$
    ⇔ $cos(3x-\dfrac{\pi}{3})=-sin(\dfrac{3\pi}{4}-x)$
    ⇔ $cos(3x-\dfrac{\pi}{3})=cos(\dfrac{\pi}{2}+\dfrac{3\pi}{4}-x)$
    ⇔ $cos(3x-\dfrac{\pi}{3})=cos(\dfrac{5\pi}{4}-x)$
    ⇔ \(\left[ \begin{array}{l}3x-\dfrac{\pi}{3}=\dfrac{5\pi}{4}-x+k2\pi\\3x-\dfrac{\pi}{3}=-\dfrac{5\pi}{4}+x+k2\pi\end{array} \right.\)
    ⇔ \(\left[ \begin{array}{l}x=\dfrac{19\pi}{48}+\dfrac{k\pi}{2}\\x=-\dfrac{11\pi}{24}+k\pi\end{array} \right.\) $(k∈\mathbb{Z})$

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