If the vectors $\bar{a}, \bar{b}, \bar{c}$ satisfy the condition $|\bar{a}-\bar{c}|=|\bar{b}-\bar{c}|$, then…
If the vectors $\bar{a}, \bar{b}, \bar{c}$ satisfy the condition $|\bar{a}-\bar{c}|=|\bar{b}-\bar{c}|$, then $(\bar{b}-\bar{a}) \cdot\left(\bar{c}-\frac{\bar{a}+\bar{b}}{2}\right)=$