Vector Algebra

$\bar{a}, \bar{b}, \bar{c}$ are non-collinear

$\overline{\mathrm{a}}, \overline{\mathrm{b}}, \overline{\mathrm{c}}$ are in the same direction

$\overline{\mathrm{a}}, \overline{\mathrm{c}}$ are in the same direction but $\overline{\mathrm{a}}, \overline{\mathrm{b}}$ are in the opposite direction

$\overline{\mathrm{c}}, \overline{\mathrm{b}}$ are in the opposite direction and $\overline{\mathrm{a}}, \overline{\mathrm{b}}$ are in the same direction