what is this triangle called

This? ( link )

I think it's called a self-supporting triangle scaffolding, but don't quote me on this.

-cb

I've seen that elsewhere, too. It's an old bar trick! Google: "Three Knifes Bar Trick." I saw it on Stargate Atlantis. Several people were trapped at the bottom of a mine shaft, but there was some scaffolding above them. So the clever doctor shows them this bar trick where you bet someone you can't support an egg over a glass of beer using three knives (or something like that) and they say you're crazy, so you take three butter knives and interlock them, so each one is over and under the ones next to it, forming a triangle in the middle that can support weight. So the trapped people take three half-rotted planks and interlock them in the same way, up on the scaffolding, and it provides a way for them to try and reach the entrance above them. Of course, one of the planks breaks because it's so old, and they fall back to the bottom of the shaft. And I think someone breaks their leg, too. But it's the same kind of thing.

Here's another YouTube video demonstrating it. (Jump to 1:38 for a photo of the trick.) I don't know if it has another name or not, I found it by searching for bar tricks.