# A cross B equals zero

1. Jul 1, 2012

### Philosophaie

A cross B equals zero is a test for orthogonal cases.

If AxB=0 then A is perpendicular to B.

2. Jul 1, 2012

### Number Nine

Uh...is that a question?

3. Jul 1, 2012

### HallsofIvy

No, it's not. It is the dot product. If A and B are vectors, the $A\cdot B= 0$ if and only if they are orthogonal (perpendicular).

You are confusing this with the fact that if A and B are any two (three dimensional) vectors, then $A\times B$ is perpendicular to both A and B.