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

Toán Lớp 11: Giai cac phuong trinh sau: `cos(x+pi/3)+sin(pi/2+2x)=0`

Tháng Một 1, 2023 Toán học 2 Comments 0 views

Toán Lớp 11: Giai cac phuong trinh sau:
cos(x+pi/3)+sin(pi/2+2x)=0

Comments ( 2 )

  1. dinhcongson
    dinhcongson
    1 Tháng Một, 2023 at 6:50 sáng
    Reply
    Bạn xem hình

    toan-lop-11-giai-cac-phuong-trinh-sau-cos-pi-3-sin-pi-2-2-0

  2. cobexinhdep
    cobexinhdep
    1 Tháng Một, 2023 at 6:49 sáng
    Reply
    ~rai~
    \(\cos\left(x+\dfrac{\pi}{3}\right)+\sin\left(\dfrac{\pi}{2}+2x\right)=0\\\Leftrightarrow \cos\left(x+\dfrac{\pi}{3}\right)+\cos2x=0\\\Leftrightarrow \cos2x=-\cos\left(x+\dfrac{\pi}{3}\right)\\\Leftrightarrow \cos2x=\cos\left(\pi-x-\dfrac{\pi}{3}\right)\\\Leftrightarrow \cos2x=\cos\left(\dfrac{2\pi}{3}-x\right)\\\Leftrightarrow \left[\begin{array}{I}2x=\dfrac{2\pi}{3}-x+k2\pi\\2x=x-\dfrac{2\pi}{3}+k2\pi\end{array}\right.\\\Leftrightarrow \left[\begin{array}{I}3x=\dfrac{2\pi}{3}+k2\pi\\x=-\dfrac{2\pi}{3}+k2\pi\end{array}\right.\\\Leftrightarrow \left[\begin{array}{I}x=\dfrac{2\pi}{9}+k\dfrac{2\pi}{3}\\x=-\dfrac{2\pi}{3}+k2\pi.\end{array}\right.\quad(k\in\mathbb{Z})\)
     

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

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