# Dot Product confusion (no calculations involved)

1. Jan 21, 2012

### LearninDaMath

If I take the Dot Product of two vectors, say A and B, I get: AxBx + AyBy + AzBz

And then when I add those terms, I get the magnitude, right?

So when one of those terms are negative, that means I could end up with a negative magnitude?

I thought magnitude had to be positive.

2. Jan 21, 2012

### I like Serena

You get the squared magnitude of a vector if you take the dot product of that vector with itself.
This is always positive (for a non-zero vector).

A dot product between 2 different vectors can be negative.
This indicates that the angle between the vectors is greater than 90 degrees.

3. Jan 23, 2012

### LearninDaMath

Thanks I like Serena, this cleared up the confusion.

4. Jan 23, 2012

Cheers!