Star Lozenge
Ivars Peterson posted a lovely mosaic today (http://mathtourist.blogspot.com/2016/11/star-of-lozenges.html) and I was interested in the pattern and whether it generalized.
So often what you find is that the artist made an optimal choice. This exact triangle is the most interesting! What must its proportions be?
But try other symmetries (N). What are the interesting triangles for those?