Let $\overline{\mathrm{a}},\overline{\mathrm{b}},\overline{\mathrm{c}}$ be three vectors having magnitudes 1, 1, 2 respectively. If $\overline{\mathrm{a}}\times \left(\overline{\mathrm{a}}\times \overline{\mathrm{c}}\right)+\overline{\mathrm{b}}=\overline{0}$ then the angle between $\overrightarrow{\mathrm{a}}$ and $\overrightarrow{\mathrm{c}}$ is