Weird, huh? I ran that by my math whiz son and he acted as if he knew exactly what this guy meant by this statement. My son says that he's referring to a triangle sitting on top of something curved, like a ball. So, the triangle would still have three sides because it doesn't matter on which surface it is sitting. He then "informed" me that the guy was simply making a joke. I told him that there were no other jokes in the article, but he insisted he was right.
In any case, I have no clue what that guy was talking about. I guess three semesters of calculus and a semester or two of vector analysis and differential equations didn't prepare me for this kind of math. I think I need to go back to school, lol.