Originally Posted by SusanErler

I just made one of those. It's called Thousand Pyramids. The triangles are all equilateral at 60 degrees. The "triangles within a triangle" are just a large triangle segmented into 4 smaller ones. Here's a good illustration:

http://www.lindafranz.com/blog/elect...iangle-quilts/

Here's a pic of mine in progress:

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