A.\(\dfrac{\pi }{2}\)
B.\(\dfrac{\pi }{3}\)
C.\(\dfrac{\pi }{4}\)
D.\(\dfrac{\pi }{6}\)

A.\(\dfrac{{k\pi }}{2}\)
B.\(k\pi \)
C.\(\dfrac{{k2\pi }}{3}\)
D.\(\dfrac{{k\pi }}{3}\)

A.\(\dfrac{\pi }{2} + k2\pi ,\,\,k \in \mathbb{Z}\)
B.\( - {270^0} + k{360^0},\,\,k \in \mathbb{Z}\)
C.\({270^0} + k{360^0},\,\,k \in \mathbb{Z}\)
D.\(\dfrac{{9\pi }}{{10}} + k2\pi ,\,\,k \in \mathbb{Z}\)

A.\(\alpha \) và \(\beta ;\,\,\gamma \)
B.\(\beta \) và \(\,\gamma \); \(\alpha \) và \(\delta \)
C.\(\alpha ,\,\,\beta ,\,\,\gamma \)
D.\(\beta ,\,\,\gamma ,\,\,\delta \)

A.\(2,77cm\)
B.\(2,9cm\)
C.\(2,76cm\)
D.\(2,8cm\)

A.\(k2\pi ,\,\,k \in \mathbb{Z}\)
B.\(\dfrac{{2\pi }}{5} + k2\pi ,\,\,k \in \mathbb{Z}\)
C.\( - \dfrac{{2\pi }}{5} + k2\pi ,\,\,k \in \mathbb{Z}\)
D.\(k\pi ,\,\,k \in \mathbb{Z}\)

A.\(\sin \alpha  > 0\)
B.\(\cos \alpha  < 0\)
C.\(\tan \alpha  < 0\)
D.\(\cot \alpha  < 0\)

A.\(1 + {\tan ^2}\alpha  = \dfrac{1}{{{{\cos }^2}\alpha }}\)
B.\(1 + {\cot ^2}\alpha  = \dfrac{1}{{{\rm{si}}{{\rm{n}}^2}\alpha }}\)
C.\(\tan \alpha  + \cot \alpha  = 2\)
D.\(\tan \alpha .\cot \alpha  = 1\)

A.\(2\sqrt 2 \)
B.\( - \sqrt 2 \)
C.\(\sqrt 2 \)
D.\(0\)

A.\({30^0}\)
B.\({40^0}\)
C.\({50^0}\)
D.\({60^0}\)