- Will two vectors that are equal to each other have the same length?
**YES**, since corresponding elements must be equal, so corresponding squares must be equal, so the sum must be equal, so the length must be equal.

- Will two vectors that have the same length always be equal to each other?
**NO**. It is possible for the sum of the squared elements to be equal without the elements themselves being equal.

If **v** is a vector, then **-v** is a vector pointing in the
opposite direction.

If **v** is represented by (a, b, c)^{T}
then **-v** is represented by (-a, -b, -c)^{T}.

What is the relation between the length of **v** and the
length of **-v**?