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: Simple matrix proof

  1. Jul 25, 2010 #1
    1. The problem statement, all variables and given/known data

    Questions on it's own are relatively simple, however, there is a bonus question which asks ''with a right choice of Theta, show how you can do question 36 easily with question 38''

    2. Relevant equations

    3. The attempt at a solution

    Attempting question 36, it is known that B^8 is the identity matrix, so B^2001 is I*B.

    Question 38 is just using some product to sum formulas etc, but I'm stuck as to how I apply question 38 to solve 36? my initial guess is Theta=pi or pi/2?

    Any hints, tips would be much appreciated.

    Attached Files:

    • 36.jpg
      File size:
      3.4 KB
    • 38.jpg
      File size:
      7.9 KB
  2. jcsd
  3. Jul 25, 2010 #2


    User Avatar
    Homework Helper

    so try and find an angle [itex] \theta [/itex] such that [itex] A(\theta) = B [/itex]

    A is a rotation matrix, and aplying A^2 rotates by twice the angle, so have a think what 2001 times the angle is for B
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook