question_answer

Let \[\vec{a},\text{ }\vec{b}\] and \[\vec{c}\] be three vectors having magnitudes 1, 1 and 2 respectively. If \[\vec{a}\times (\vec{a}\times \vec{c})+\vec{b}=\vec{0}\], then the acute angle between \[\vec{a}\] and\[\vec{c}\]is______.

A)  \[\frac{\pi }{4}\]                       

B)  \[\frac{\pi }{6}\]           

C)  \[\frac{\pi }{3}\]                       

D)  None of these