Given that we have $x=x' \cos \theta - y' \sin \theta $ and $y=x' \sin \theta +y' \cos \theta $ ,how can I express $x',y'$ in terms of $x,y$ and $a$ ?
I've browsed through the site to seek for some help but I've found that most of the questions involving rotation of coordinates involve the knowledge of matrices or vectors which I haven't yet studied.
Can you guys help me solve the problem without the use of matrices,or vectors or some other too advanced technique (for my level) ?
I've not been able to make any usefull attempt as I haven't clear in my mind how to get started.
Thanks in advance.