Question
Suppose $(\vec{a} + \vec{b} + \vec{c} = 0)$, $(|\vec{b}| = 5)$, $(|\vec{c}| = 7)$, then the angle between $(\vec{a})$ and $(\vec{b})$ is
Suppose $(\vec{a} + \vec{b} + \vec{c} = 0)$, $(|\vec{b}| = 5)$, $(|\vec{c}| = 7)$, then the angle between $(\vec{a})$ and $(\vec{b})$ is