Rotation axix calculation

Hi,
I require a forumla to calculate the following...

I have a car in 2d space... and when i rotate the car by r radians i want a formula which will give me the new x and y value of the car if it was moved by distance of say n unit in any of the 4 direction..



so in short i want rotate the car in r radians and to move the car in 4 directions -x,+x,y,+y and the formula should give me the new computed X and Y value...


This is not home work.. it is for my VRMLstuff i am working on.....


thanx in advance