Toán sin(x-120 độ)=cos 5x Mn giúp mình vs mai ktra rùi huhu :(( 01/10/2021 By Faith sin(x-120 độ)=cos 5x Mn giúp mình vs mai ktra rùi huhu :((
Ta có $\sin(x – 120^{\circ}) = \sin(\pi/2 – 5x)$ <->$ x – 2\pi/3 = \pi/2 – 5x + 2k\pi$ hoặc $x – 2\pi/3 = \pi – (\pi/2 – 5x) + 2k\pi$ <->$ x = -\pi/36 + k\pi/3$ hoặc $x = -\pi/24 + k\pi/2$ Trả lời
Ta có
$\sin(x – 120^{\circ}) = \sin(\pi/2 – 5x)$
<->$ x – 2\pi/3 = \pi/2 – 5x + 2k\pi$ hoặc $x – 2\pi/3 = \pi – (\pi/2 – 5x) + 2k\pi$
<->$ x = -\pi/36 + k\pi/3$ hoặc $x = -\pi/24 + k\pi/2$