If $\bar{a}$ and $\bar{b}$ are two vectors such that $|\vec{a}|=|\vec{b}|=\sqrt{2}$ with $\vec{a} \cdot…
If $\bar{a}$ and $\bar{b}$ are two vectors such that $|\vec{a}|=|\vec{b}|=\sqrt{2}$ with $\vec{a} \cdot \vec{b}=-1$, then the angle between $\bar{a}$ and $\bar{b}$ is