Vector Algebra

Vectors \(\overline{\mathrm{a}}\) and \(\overline{\mathrm{b}}\) are such that \(|\overline{\mathrm{a}}|=1 ;|\overline{\mathrm{b}}|=4\) and \(\bar{a} \cdot \bar{b}=2\). If \(\bar{c}=2 \bar{a} \times \bar{b}-3 \bar{b}\), then the angle between \(\bar{b}\) and \(\bar{c}\) is