It's 1am and I can't think straight any more... I've got a graphic of a tandem and a trailer, which I'm animating using nulls so that the wheels always touch the ground. I got the tandem wheels working, but am having trouble with the trailer... basically I think this could be summarised as "from the diagram below, what's the formula to make B always touch the line between C and D?" The positions of A, C and D are known, as is the length ab. (A is the "hinge" connecting the trailer to the bike, C is the bike's rear wheel contact point, B is the trailer wheel's contact point defined by a point control that doesn't move, and D is a null that can pretty much go wherever it wants to.)
At this point I'm just going round in circles, any help would be appreciated!
