Try and figure it out before continuing on. Some people intuitively "get" it, but you have to understand what's going on. Other people don't get it, even once it's been explained to them.

This is obviously impossible. If the triangles are the same size, then how can we create an area that has 1 extra space? And it's obvious that the triangles are the same size - 8 long by 3 high, and 5 long by 2 high.