Trong các khẳng định sau khẳng định nào đúng?
A.\(\cot \alpha \tan \alpha = 1,\quad \alpha \ne \dfrac{{k\pi }}{2},k \in Z\)
B.\(1 + {\tan ^2}\alpha = \dfrac{1}{{{{\cos }^2}\alpha }},{\text{ }}\alpha \ne {\text{k}}\pi {\text{, k}} \in Z\)
C.\({\sin ^2}\alpha + c{\text{o}}{{\text{s}}^2}\beta = 1\)
D. \(1 + {\cot ^2}\alpha = \dfrac{1}{{{{\sin }^2}\alpha }},{\text{ }}\alpha \ne \dfrac{\pi }{2}{\text{ + k}}\pi {\text{, k}} \in Z\)
A.\(\cot \alpha \tan \alpha = 1,\quad \alpha \ne \dfrac{{k\pi }}{2},k \in Z\)
B.\(1 + {\tan ^2}\alpha = \dfrac{1}{{{{\cos }^2}\alpha }},{\text{ }}\alpha \ne {\text{k}}\pi {\text{, k}} \in Z\)
C.\({\sin ^2}\alpha + c{\text{o}}{{\text{s}}^2}\beta = 1\)
D. \(1 + {\cot ^2}\alpha = \dfrac{1}{{{{\sin }^2}\alpha }},{\text{ }}\alpha \ne \dfrac{\pi }{2}{\text{ + k}}\pi {\text{, k}} \in Z\)
Loga
Hóa Học lớp 12
