Question

Can't get B part, I did part a but not sure if right.

Answer 1

\(\vec{u}\cdot\vec{v} =|\vec{u}|\vec{v}|\cos(\theta)\)
From the given question, it means that \(\cos(\theta)=1\)

Think of the angle(s) which make \(\cos(\theta)=1\) true. What does that say about the position of the vectors?

Answer 2

would this be right?

u ⃗xv ⃗=|u ⃗ ||v ⃗ | cos⁡〖<u ⃗,v ⃗>-|u ⃗ ||v ⃗ |〗
|u ⃗ ||(v ) ⃗ |(cos<u ⃗,v ⃗> -1)=0
|u ⃗ ||v ⃗ |=0 or cos⁡〖<u ⃗,v ⃗>-1=0〗
at least one of the two vectors is collinear and in the same direction

Answer 3

perps are dot products equal to 0