Phương trình \({\sin ^2}x + {\cos ^2}4x = 1\) có nghiệm là:
A.\(\left[ \matrix{x = {{k\pi } \over {13}} \hfill \cr x = {{k\pi } \over 5} \hfill \cr} \right.\,\,\,\left( {k \in Z} \right)\)
B.\(\left[ \matrix{x = {{k\pi } \over {23}} \hfill \cr x = {{k\pi } \over {25}} \hfill \cr} \right.\,\,\,\left( {k \in Z} \right)\)
C.\(\left[ \matrix{x = {{k\pi } \over 3} \hfill \cr x = {{k\pi } \over 5} \hfill \cr} \right.\,\,\,\left( {k \in Z} \right)\)
D.\(\left[ \matrix{x = {{k\pi } \over 3} \hfill \cr x = {{k\pi } \over {35}} \hfill \cr} \right.\,\,\,\left( {k \in Z} \right)\)