Biết \(\tan \alpha  = 2\), tính \(\cot \alpha \)

A. \(\cot \alpha  = \frac{1}{{\sqrt 2 }}\\)

B. \(\cot \alpha  = \frac{-1}{{\sqrt 2 }}\\)

C. \(\cot \alpha  = \frac{1}{2}\)

D. \(\cot \alpha  = \frac{-1}{2}\)