This puzzle consists of counting ten triangles (check three sides for each one, remember that there aren't exist triangles with more than three sides :P ) using two straight lines that cross the figure wherever you want.
You can't count a triangle that contains other triangles inside. I mean, every triangle has to have an empty area inside. Here is an example of the game:
Is kind of easy to find nine triangles, but I only could find one solution that solves the problem. Good luck! Ask me if you don't understand the rules!