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

Toán Lớp 11: giải phương trình cos 5 x – sin 3x = 0

Toán Lớp 11: giải phương trình cos 5 x – sin 3x = 0

Comments ( 1 )

  1. $cos5x-sin3x=0$
    $⇔cos5x=sin3x$
    $⇔cos5x=cos\bigg(\dfrac{\pi}{2}-3x\bigg)$
    $⇔$\(\left[ \begin{array}{l}5x=\dfrac{\pi}{2}-3x+k2\pi\\5x=-\dfrac{\pi}{2}+3x+k2\pi\end{array} \right.\) 
    $⇔$\(\left[ \begin{array}{l}8x=\dfrac{\pi}{2}+k2\pi\\2x=-\dfrac{\pi}{2}+k2\pi\end{array} \right.\)
    $⇔$\(\left[ \begin{array}{l}x=\dfrac{\pi}{16}+\dfrac{k\pi}{4}\\x=-\dfrac{\pi}{4}+k\pi\end{array} \right.\)$(k∈Z)$

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