# Math Help - Help needed on Vectors and Perpendicularity.

1. ## Help needed on Vectors and Perpendicularity

Find two unit vectors perpenduicular to both $\vec{v}$ and $\vec{w}$ where $\vec{v}$ = i + 2j - 7k and $\vec{w}$ = 5i + j + k

thanks!

2. Originally Posted by rorosingsong
Find two unit vectors perpenduicular to both $\vec{v}$ and $\vec{w}$ where $\vec{v}$ = i + 2j - 7k and $\vec{w}$ = 5i + j + k
Find $\vec{u}=
\dfrac{\vec{v}\times\vec{w}}{\|\vec{v}\times\vec{w }\|}.$

Then $\vec{u}~\&-\vec{u}$ will work.

3. Whoops, just realised I posted this in calculus -- sorry, meant to do it in linear algebra!

Sorry guys.

4. In fact, it is more a Calculus problem than Linear Algebra because it refers to vector in $R^n$, not a general vector space.