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

Toán Lớp 11: Giúp em với ạ cos ( x – 2π/3 ) + sin2x = 0

Toán Lớp 11: Giúp em với ạ
cos ( x – 2π/3 ) + sin2x = 0

Comments ( 1 )

  1. cos (x – (2π)/3) + sin2x = 0
    ⇔cos (x – (2π)/3)=-sin(2x)
    ⇔cos (x – (2π)/3)=cos (π/2 + 2x)
    ⇔ $\left[\begin{matrix} x-\dfrac{2π}{3}=\dfrac{π}{2}+2x+k2π\\ x-\dfrac{2π}{3}=-\dfrac{π}{2}-2x+k2π\end{matrix}\right.$
    ⇔ $\left[\begin{matrix} x=-\dfrac{7π}{6}+k2π\\ x=\dfrac{π}{18}+k\dfrac{2π}{3}\end{matrix}\right.$
     

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

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