Snagged a little on some vector math

[whiterabbit9]

I'm learning how to calculate E-fields and, in some examples, when using the unit vector r^ with only one component (ie r^x or r^y), it is simply defined r^x=x/r. I am missing the algebra. Will anyone explain this to me? Thanks

 

[vanhees71]

Bei definition the radial unit vector ist $\hat{r}=\vec{r}/r$. In Cartesian coordinates, you have $\hat{r}=(x/r,y/r,z/r)$ with $r=\sqrt{x^2+y^2+z^2}$.