Vector perpendicular to two vectors

[aigerimzh]

Homework Statement

A=(i+j-k) B=(2i-j+3k)
Need to find vector perpenducilar to them

Homework Equations

The Attempt at a Solution

I've solved by finding A*B and then divided it to (A*B), the result was W=2i/\sqrt{38}-5j/\sqrt{38}-3k/\sqrt{38}. Is it correct?

 

[HallsofIvy]

What do you mean by A*B? I know scalar product, dot product, and cross product of vectors but none of those use "*". And what is the difference between "A*B" and "(A*B)"? If you mean |A*B|, the length of the vector, I see no reason to divide. The problem did not ask for a unit vector.

 

[aigerimzh]

I mean AxB, and (AxB) means length of AxB. Do mean that my answer is not correct?

 

[HallsofIvy]

No, I meant that I did not understand your answer. Yes, AxB is perpendicular to A and B and so satisfies the condition of the problem. And so AxB/|AxB| is a unit vector perpendicular to both A and B. But the problem did not ask for a unit vector.