Chóp S.ABC, \(SA\bot \left( ABC \right),\,\,SA=a,\...

Câu hỏi: Chóp S.ABC, \(SA\bot \left( ABC \right),\,\,SA=a,\,\,\Delta ABC\) đều \(AB=a\). Tính \(\widehat{\left( \left( SBC \right);\left( ABC \right) \right)}\).

A  \(\arctan 2\)                            

B \(\arctan \frac{2}{\sqrt{3}}\)                         

C  \(\arctan \frac{1}{\sqrt{3}}\)                                    

D  \(\arctan \frac{2}{3}\)