Orthogonal Matrix - Linear Algebra

[carrotcake10]

Homework Statement

[PLAIN]http://img504.imageshack.us/img504/4985/capturewm.jpg

Homework Equations

N/A

The Attempt at a Solution

This is more of a conceptual question so I need a little help knowing what kinds of things to look for.

 

[zachzach]

Well what does it mean for a matrix to be orthogonal?