If $\vec{a}$, $\vec{b}$ and $\vec{c}$ are vectors such that $\vec{a}$+$\vec{b}$+$\vec{c}$ = 0 and |$\vec{a}$| =7, $\vec{b}$=5,  |$\vec{c}$| = 3, then the angle between the vectors $\vec{b}$ and $\vec{c}$