Vector Algebra

Let \(\bar{a}, \bar{b}\) and \(\bar{c}\) be three unit vectors such that \(\bar{a} \times(\bar{b} \times \bar{c})=\frac{\sqrt{3}}{2}(\bar{b}+\bar{c})\). If \(\bar{b}\) is not parallel to \(\bar{c}\), then the angle between \(\bar{a}\) and \(\bar{b}\) is