If I have perpendicular vectors $ \vec{a}$ and $\vec{b} $, then $\vec{a}.\vec{b} = 0$. What happens if they are co-linear? Would you just get $\vec{a}.\vec{b} = ||\vec{a}||.||\vec{b}|| . 1 $?
Also, does $\vec{a}$ x $\vec{b} = 0$ if they're co-linear?