Orthogonal rotation

[Petrus]

Hello MHB,
Do anyone know any good page that give you good describe when you rotate with orthogonal. I mean when you rotate base or vector in a orthogonal base ( hope this make sense) cause I did not understand from my book

Regards,
\(\displaystyle |\pi\rangle\)

 

[Ackbach]

I like the wiki on rotation matrices myself.