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

Toán Lớp 11: ai chỉ mính với sin3x = sin ( 2x + π/4 ) làm sao ạ

Toán Lớp 11: ai chỉ mính với
sin3x = sin ( 2x + π/4 )
làm sao ạ

Comments ( 2 )

  1. Giải đáp:
     
    Lời giải và giải thích chi tiết:
     sin\ 3x=sin\ (2x+\frac{\pi}{4})
    ⇔ \(\left[ \begin{array}{l}3x=2x+\dfrac{\pi}{4}+k2\pi\ (k \in \mathbb{Z})\\3x=\pi-2x-\dfrac{\pi}{4}+k2\pi\ (k \in \mathbb{Z})\end{array} \right.\) 
    ⇔ \(\left[ \begin{array}{l}x=\dfrac{\pi}{4}+k2\pi\ (k \in \mathbb{Z})\\5x=\pi-\dfrac{\pi}{4}+k2\pi\ (k \in \mathbb{Z})\end{array} \right.\) 
    ⇔ \(\left[ \begin{array}{l}x=\dfrac{\pi}{4}+k2\pi\ (k \in \mathbb{Z})\\5x=\dfrac{3\pi}{4}+k2\pi\ (k \in \mathbb{Z})\end{array} \right.\) 
    ⇔ \(\left[ \begin{array}{l}x=\dfrac{\pi}{4}+k2\pi\ (k \in \mathbb{Z})\\x=\dfrac{3\pi}{20}+k\dfrac{2\pi}{5}\ (k \in \mathbb{Z})\end{array} \right.\) 
    Vậy S={\frac{\pi}{4}+k2\pi\ (k \in \mathbb{Z});\frac{3\pi}{20}+k\frac{2\pi}{5}\ (k \in \mathbb{Z})}

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

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