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!

Calculating angle between two vectors

  1. Sep 10, 2010 #1
    1. The problem statement, all variables and given/known data

    Use the definition of scalar product, a·b = ab cos θ, and the fact that a·b = axbx + ayby + azbz to calculate the angle between the two vectors given by a = 1.0 ihat + 5.0 jhat + 1.0 khat and b = 6.0 ihat + 3.0 jhat + 4.0 khat.

    2. Relevant equations

    a·b = ab cos θ

    3. The attempt at a solution

    i really dont have any clue were to start
  2. jcsd
  3. Sep 10, 2010 #2

    Andrew Mason

    User Avatar
    Science Advisor
    Homework Helper

    Write out the expression for [itex]\theta[/itex] in terms of the length of a x length of b and [itex]a_xb_x + a_yb_y + a_zb_z[/itex] (hint: you need the arccos function and pythagoras' theorem).

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Calculating angle between two vectors