http://i39.tinypic.com/2qvfrya.jpg That is the problem that I am trying to solve. It is simply a practice question but I want to make sure that I am doing things right and that I am prepared. I understand the concept of this problem and have modeled the problem on paper with triangles. I just don't understand where to get started. I am sorry if this is vague, but even the smallest hint will probably help because I have done this work before two years ago in high school, but I am at university now with a mediocre lecturer and unfortunately some of the material isn't clicking like it should. Thanks for any replies!