Tìm nghiệm của phương trình \(\cos x + \sqrt 3 \sin x = \sqrt 3 \).

A. \(\left[ \begin{array}{l}
x = \frac{\pi }{2} + k2\pi \\
x = \frac{\pi }{6} + k2\pi \,\,\,
\end{array} \right.\,\,\,\,\,\left( {k \in Z} \right)\)

B. \(\left[ \begin{array}{l}
x = {30^0} + k{180^0}\\
x = {90^0} + k{180^0}\,\,\,
\end{array} \right.\,\,\,\,\,\left( {k \in Z} \right)\)

C. \(x = \frac{\pi }{3} + k\pi \,\,\,\left( {k \in Z} \right)\)

D. \(\left[ \begin{array}{l}
x = \frac{\pi }{2} + k{360^0}\\
x = \frac{\pi }{6} + k{360^0}\,\,\,
\end{array} \right.\,\,\,\,\,\left( {k \in Z} \right)\)