Boundary Conditions

In order to keep all the outputs matching up we will impose boundary conditions. So, if the new road falls upon line (B,E') then TURN RIGHT, if it falls upon line (B,F') then GO STRAIGHT, and if it falls upon line (A,B) you're in trouble because you shouldn't have two roads on top of each other.

In order to find the angle between points A,B, and C you could use the Law of Cosine or arccos to derive a formula that would give you the answer OR you could be a savvy Java programming and use one function from the Java API that gives you the angle. Your choice.