Phương trình \(\cot 2x.\sin 3x = 0\) có nghiệm là:
A.\(\left[ \matrix{x = {\pi \over 4} + {{k\pi } \over 2} \hfill \cr x = {{2k\pi } \over 3} \hfill \cr} \right.\,\,\left( {k \in Z} \right)\)
B.\(\left[ \matrix{x = {\pi \over 4} + {{k\pi } \over 2} \hfill \cr x = {{k\pi } \over 3} \hfill \cr} \right.\,\,\left( {k \ne 3m;k \in Z} \right)\)
C.\(\left[ \matrix{x = {\pi \over 4} + k\pi \hfill \cr x = {{k\pi } \over 3} \hfill \cr} \right.\,\,\left( {k \ne 3m;k \in Z} \right)\)
D.\(\left[ \matrix{x = {\pi \over 3} + {{k\pi } \over 2} \hfill \cr x = {{2k\pi } \over 3} \hfill \cr} \right.\,\,\left( {k \in Z} \right)\)