Toán Lớp 11: (2 sin(x) – cos(x) ) ( 1 + cos(x)) = $sin(x)^{2}$
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5 sao + ctlhn nha
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Toán Lớp 11: (2 sin(x) – cos(x) ) ( 1 + cos(x)) = $sin(x)^{2}$
giải hộ PT trên đc ko
5 sao + ctlhn nha
Comments ( 2 )
\left( {2\sin \,x – \cos \,x} \right)\left( {1 + \cos \,x} \right) = {\sin ^2}x\\
\Leftrightarrow 2\sin \,x + 2\sin \,x\,\,\cos \,x – \cos \,x – {\cos ^2}\,x\\
\Leftrightarrow \left( {2\,\sin \,x – 1} \right)\left( {\cos \,x + 1} \right) = 0\\
\Leftrightarrow \left[ \begin{array}{l}
\sin \,x = \frac{1}{2}\\
\cos \,x = – 1
\end{array} \right.\,\, \Leftrightarrow \left[ \begin{array}{l}
\frac{\pi }{6} = – 1\\
\frac{{5\pi }}{6} + k2\pi \\
\pi + k2\pi
\end{array} \right.
\end{array}\]