I don't know if I am misunderstanding the question. How can I get the vector from the magnitude unless I know the direction of the vector that results in that magnitude?
Find the vector c that has a magnitude of half that of the vector ${\bf b} = (-2,1,3)$.
So I get that the result $1/2||b|| = ||c||$
But I don't know how I am suppossed to find $c=(x,y,z)$? It could be multiple different answers.
Am I misunderstanding the question?
EDIT:
Yeah I think it is a poorly worded, sorry to bother you with this. I guess it might be helpful for someone who wants to know if you can find a vector from magnitude.