\(f(x) = \dfrac{1}{{\sin x}}\) trên đoạn \(\left[ {\dfrac{\pi }{3};\dfrac{{5\pi }}{6}} \right]\)
A.\(\mathop {\min }\limits_{\left[ {\dfrac{\pi }{3};\dfrac{{5\pi }}{6}} \right]} f(x) = 1;\mathop {\max }\limits_{\left[ {\dfrac{\pi }{3};\dfrac{{5\pi }}{6}} \right]} f(x) = 2\).
B.\(\mathop {\min }\limits_{\left[ {\dfrac{\pi }{3};\dfrac{{5\pi }}{6}} \right]} f(x) =- 1;\mathop {\max }\limits_{\left[ {\dfrac{\pi }{3};\dfrac{{5\pi }}{6}} \right]} f(x) = 2\).
C.\(\mathop {\min }\limits_{\left[ {\dfrac{\pi }{3};\dfrac{{5\pi }}{6}} \right]} f(x) = -2;\mathop {\max }\limits_{\left[ {\dfrac{\pi }{3};\dfrac{{5\pi }}{6}} \right]} f(x) = 1\).
D.\(\mathop {\min }\limits_{\left[ {\dfrac{\pi }{3};\dfrac{{5\pi }}{6}} \right]} f(x) = -2;\mathop {\max }\limits_{\left[ {\dfrac{\pi }{3};\dfrac{{5\pi }}{6}} \right]} f(x) = -1\).