Phương trình \(\sqrt 3 \cos 3x + \sin 3x = \sqrt 2...

Câu hỏi: Phương trình \(\sqrt 3 \cos 3x + \sin 3x = \sqrt 2 \) có nghiệm là:

A \(\left[ \matrix{ x = - {\pi \over {36}} + {{k2\pi } \over 3} \hfill \cr x = {{5\pi } \over {36}} + {{k2\pi } \over 3}\, \hfill \cr} \right.\,\,\,\,\left( {k \in Z} \right)\)

B \(\left[ \matrix{ x = - {\pi \over {36}} + {{k\pi } \over 3} \hfill \cr x = {{5\pi } \over {36}} + {{k\pi } \over 3}\, \hfill \cr} \right.\,\,\,\,\left( {k \in Z} \right)\)

C \(\left[ \matrix{ x = {\pi \over {36}} + {{k2\pi } \over 3} \hfill \cr x = - {{5\pi } \over {36}} + {{k2\pi } \over 3}\, \hfill \cr} \right.\,\,\,\,\left( {k \in } \right)\)

D \(\left[ \matrix{ x = - {\pi \over {36}} + k2\pi \hfill \cr x = {{5\pi } \over {36}} + k2\pi \, \hfill \cr} \right.\,\,\,\,\left( {k \in Z} \right)\)