Toán Lớp 11: Giải phương trình
cos(x-2) =sin 3(x-π/2)
Leave a reply
Register Now
Login
Lost Password
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Toán Lớp 11: Giải phương trình
cos(x-2) =sin 3(x-π/2)
Comments ( 2 )
\cos \left( {x – 2} \right) = \sin 3\left( {x – \dfrac{\pi }{2}} \right)\\
\Leftrightarrow \cos \left( {x – 2} \right) = \sin \left( {3x – \dfrac{{3\pi }}{2}} \right)\\
\Leftrightarrow \cos \left( {x – 2} \right) = \sin \left( {\dfrac{\pi }{2} +\left( { – 2\pi + 3x} \right)} \right)\\
\Leftrightarrow \cos \left( {x – 2} \right) = \cos \left( {3x – 2\pi } \right)\\
\Leftrightarrow \cos \left( {x – 2} \right) = \cos 3x\\
\Leftrightarrow \left[ \begin{array}{l}
x – 2 = 3x + k2\pi \\
x – 2 = – 3x + k2\pi
\end{array} \right.\\
\Leftrightarrow \left[ \begin{array}{l}
x = – 1 – k\pi \\
x = \dfrac{1}{2} + \dfrac{{k\pi }}{2}
\end{array} \right.\left( {k \in \mathbb{Z}} \right)
\end{array}$