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: Rotation Matrices

  1. Mar 9, 2010 #1
    [URGENT] Rotation Matrices

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

    http://e.imagehost.org/0661/Screen_shot_2010-03-09_at_12_37_44_AM.png [Broken]

    2. Relevant equations

    Rotation Matrix:
    cos(theta) -sin(theta)
    sin(theta) cos(theta)

    3. The attempt at a solution

    I understand 2a:

    cos(pi/4) -sin(pi/4)
    sin(pi/4) cos(pi/4)

    But I am not sure what 2b is looking for. Please help?

    Thank you in advance for your help!
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Mar 9, 2010 #2


    User Avatar
    Homework Helper

    Re: [URGENT] Rotation Matrices

    The matrix you wrote is a rotation matrix, which rotates a vector but leaves its length unchanged. You need a matrix which doubles the length as well. Try to find such one.

    Last edited: Mar 9, 2010
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook