Circular "Vortex" Movement

[Soilydude]

I want to create an object which will have circular movement similar to an old iPod game called Vortex. I'd like it to work so that when the player presses the left arrow key the object moves along the circumference in an anti-clockwise direction. The same would happen if the player pressed the right arrow key but in a clockwise direction.

I haven't really got the first idea of how to do this so if someone could point me in the right direction I would be eternally grateful

[happygreenfrog]

http://community.clickteam.com/threads/60440-Tutorial-Trigonometry-In-Gaming

There is an example in the thread I just linked to above. It's an article that explains trigonometry for game programming purposes (it's explained in an easy way, don't worry).