# Homework Help: Simple matrix proof

1. Jul 25, 2010

### Gameowner

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.

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2. Jul 25, 2010

### lanedance

so try and find an angle $\theta$ such that $A(\theta) = B$

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