Giải phương trình: \(\sqrt 3 {\cot ^2}x + \left( {1 - \sqrt 3 } \right)\cot x - 1 = 0.\)
A.\(S = \left\{ {\dfrac{\pi }{4} + k\pi ; - \dfrac{\pi }{3} + k\pi } \right\}\)
B.\(S = \left\{ {\dfrac{\pi }{4} + k\pi ; \dfrac{\pi }{3} + k\pi } \right\}\)
C.\(S = \left\{ {-\dfrac{\pi }{4} + k\pi ; - \dfrac{\pi }{3} + k\pi } \right\}\)
D.\(S = \left\{ {-\dfrac{\pi }{4} + k\pi ; \dfrac{\pi }{3} + k\pi } \right\}\)