# Perpendicular vectors

• Mar 7th 2011, 02:51 PM
Barthayn
Perpendicular vectors
I have a question dealing with perpendicular vectors. In the book it states this;

10. Find a vector that is perpendicular to both given vectors.
a) u = [1, 2, 3], v = [3, 2, 1]

The answer I got was n = [1, -2, 1] but the book has it as a multiple of -4, which is [-4, 8, -4]. Why is it -4?
• Mar 7th 2011, 03:03 PM
Plato
Quote:

Originally Posted by Barthayn
10. Find a vector that is perpendicular to both given vectors. a) u = [1, 2, 3], v = [3, 2, 1]
The answer I got was n = [1, -2, 1] but the book has it as a multiple of -4, which is [-4, 8, -4]. Why is it -4?

The book's answer happens to be $u\times v$.
But any multiple of that vector is also a correct answer.
So yours is correct,