1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Dot Product of Equilateral Triangle

  1. Jun 2, 2014 #1
    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. jcsd
  3. Jun 2, 2014 #2

    benorin

    User Avatar
    Homework Helper

    ...the dot products are the cosine of the angle between them.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Loading...