# Finding unit vector perpendicular to U

given u=[0,4,3]T a unit vector that is prependicular to u is

How can I find the normal?

I am new to these stuff.

Thanks

• In tridimensional space there are a plane of perpendicular vectors to $u$. – Sigur Dec 6 '13 at 17:33
• Just find "by inspection" any vector which has a zero scalar product with your vector. Then divide by its length to get a unit vector. – Old John Dec 6 '13 at 17:39
• what if they ask for a vector parallel to u – user107895 Dec 6 '13 at 17:46
• math.stackexchange.com/questions/133177/… there is complete answer ,please see it – dato datuashvili Dec 6 '13 at 17:55
• please see answer if it is enough – dato datuashvili Dec 6 '13 at 18:03

ok in your case vector is simple $u=[0,4,3]$,for some vector s,we say that $s$ is perpendicular to $u$,if $s*u=0$,so let us suppose that
$s=(s_1,s_2,s_3)$ ,so we have
$S_1*0+s_2*4+s_3*3=0$,
• choose any values of $x$,$b$ and $c$ which satisfy these solution,but to gain unit vector,divide this vector by its length – dato datuashvili Dec 6 '13 at 20:07