# Dot Product of Equilateral Triangle

1. Jun 2, 2014

### mill

1. The problem statement, all variables and given/known data

In an equilateral triangle with sides u, v, w, where they are all unit vectors, find u dot w.

2. Relevant equations

u dot w = |u||w|cosθ
3. The attempt at a solution

The answer is $\frac {-1} {2}$

cos(120) = -1/2

Elsewhere, I read the statement that since these are already unit vectors then the dot products are simply the angles between them. What does this mean? Does something cancel out the |u||w| in the denominator? Or do |u||w| function to make the dot in terms of unit vectors so they would both be 1 in this case?

Nevermind, got it.

Last edited: Jun 2, 2014
2. Jun 2, 2014

### benorin

...the dot products are the cosine of the angle between them.