Nghiệm của phương trình \(2\cos x - 1 = 0\) là:

\(R\backslash \left\{ {k\pi ,k \in Z} \right\}\)

\(R\backslash \left\{ {\dfrac{{k\pi }}{2},k \in Z} \right\}\)

\(R\backslash \left\{ {\dfrac{\pi }{2} + k\pi ,k \in Z} \right\}\)

\(R\)

\(\max y =  - 2,\min y = 4\)

\(\max y = 2,\min y = 4\)

\(\max y =  - 2,\min y = 3\)

\(\max y = 4,\min y =  - 2\)

\(D = \mathbb{R}\backslash \left\{ {\dfrac{{k2\pi }}{3},k \in \mathbb{Z}} \right\}\)      

\(D = \mathbb{R}\backslash \left\{ {\dfrac{\pi }{6} + \dfrac{{k\pi }}{3},k \in \mathbb{Z}} \right\}\)

\(D = \mathbb{R}\backslash \left\{ {\dfrac{{k\pi }}{3},k \in \mathbb{Z}} \right\}\)

\(D = \mathbb{R}\backslash \left\{ {\dfrac{{k\pi }}{2},k \in \mathbb{Z}} \right\}\)

\(\left[ \begin{array}{l}x = \alpha  + k\pi \\x = \pi  - \alpha  + k\pi \end{array} \right.\left( {k \in Z} \right)\)    

\(\left[ \begin{array}{l}x = \alpha  + k2\pi \\x = \pi  - \alpha  + k2\pi \end{array} \right.\left( {k \in Z} \right)\)

\(\left[ \begin{array}{l}x = \alpha  + k2\pi \\x =  - \alpha  + k2\pi \end{array} \right.\left( {k \in Z} \right)\)      

\(\left[ \begin{array}{l}x = \alpha  + k\pi \\x =  - \alpha  + k\pi \end{array} \right.\left( {k \in Z} \right)\)

\(y = \cot x\)

\(y = \tan x\)   

\(y = \sin x\)

\(y = \cos x\)

$k2\pi \left( {k \in Z} \right)$

$k2\pi ;\dfrac{\pi }{2} + k2\pi \left( {k \in Z} \right)$

$\dfrac{{k\pi }}{2}\left( {k \in Z} \right)$

$k\pi ;\dfrac{\pi }{2} + k2\pi \left( {k \in Z} \right)$