@chris, there is an example for drawing angled lines in the FPS example sketch. If you want to draw lines at a specified angle there is an example in the clockface sketch supplied in the download, although that code is highly optimized (it uses a sin table instead of floating point) and is a little obscure.
If RAM or performance are not a concern then you can use trionometry to calculate the coordinates. If you need it, you can find a trig primer here: http://processing.org/learning/trig/