# Rotation Matrices

[URGENT] Rotation Matrices

## Homework Statement

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

## Homework Equations

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

## The Attempt at a Solution

I understand 2a:

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

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ehild
Homework Helper

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.

ehild

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