Accurate Bouncing Off An Angled Surface

Hey, i post here in hope someone can answer my question :)

How would i make a ball bounce off an angled surface? I have it bouncing off a horizontal and vertical and i have the accurate bounce sorted (Gravity, friction), but i'm stumped when it comes to angled surfaces.

I have a feeling it is to do with reflection, Ri (reflected) is R + (2N * - N . R);

Where N is the normal. However, even if it is achieved by this method, i am stuck on how to use it.

Just for clarity:

http://img12.imageshack.us/img12/7509/example0xv.png

Any help would be greatly appreciated : D