1. The problem statement, all variables and given/known data In a convex polygon of 6 sides, 2 diagonals are selected at random. The probability that they intersect in the interior of the polygon is 2. Relevant equations 3. The attempt at a solution There are 9 diagonals in a polygon of 6 sides. Therefore the total cases are 9C2. But how would i go about finding the favourable cases? I don't have a clue on how to proceed further. I basically can't understand how can i show that the diagonals intersect in the interior of the polygon. Any help is appreciated!