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

Toán Lớp 11: Giúp mik vs gắp lắm, mik cảm ơn Cos(x+π/3) = -1/2

Tháng Tám 17, 2022 Toán học 2 Comments 0 views

Toán Lớp 11: Giúp mik vs gắp lắm, mik cảm ơn
Cos(x+π/3) = -1/2

Comments ( 2 )

  1. tuyetanhthu
    tuyetanhthu
    17 Tháng Tám, 2022 at 5:17 chiều
    Reply
    cos(x+\frac{π}{3})=-\frac{1}{2}
    ⇔ cos(x+\frac{π}{3})=cos\frac{2π}{3}
    ⇔ $\left [\begin{array}{l} x+\dfrac{\pi}{3}=\dfrac{2π}{3}+k2π \\ x+\dfrac{\pi}{3}=-\dfrac{2π}{3}+k2π \end{array} \right.$
    ⇔ $\left [\begin{array}{l} x=\dfrac{\pi}{3}+k2π \\ x=-\pi+k2π \end{array} \right. \ (k∈\mathbb{Z})$

  2. buithaianh98
    buithaianh98
    17 Tháng Tám, 2022 at 5:17 chiều
    Reply
    $\cos \left(x+\dfrac \pi 3\right)=-\dfrac12$
    \(⇔ \left[ \begin{array}{l}x+\dfrac \pi 3=\dfrac{2\pi}3+k2\pi\\x+\dfrac \pi 3=-\dfrac{2\pi}3+k2\pi\end{array} \right.\) 
    \(⇔ \left[ \begin{array}{l}x=\dfrac{\pi}3+k2\pi\\x+\dfrac \pi 3=-\dfrac{3\pi}3+k2\pi\end{array} \right. (k\in \mathbb{Z})\) 

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

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