# How to write unit vector

1. Aug 8, 2008

### franky2727

i get that a unit vector is U/modU but how would it be writen for example 8i-4j-8k would it be simply (8i-4j-8k)/144?

2. Aug 8, 2008

### CompuChip

Notation for the normalized vector $\vec u$ is also $\hat u$. Note, that it is $\vec u / ||\vec u||$ and not $\vec u / || \vec u ||^2$.

3. Aug 8, 2008

### franky2727

ah sorry i ment over root 144 . apart from that is the way i wrote it fine or would i have to split it into I J and K parts?

4. Aug 8, 2008

### CompuChip

It doesn't matter;

(8i-4j-8k)/12 = (8/12) i - (4/12) j - (8/12) k.

5. Aug 8, 2008

### HallsofIvy

Staff Emeritus
Or even better (2/3)i- (1/3)j- (2/3)k :tongue2:

6. Aug 8, 2008

### CompuChip

Which is then again equivalent to
(2i - j - 2k) / 3
or
2(i - 1/2 j - k) / 3