A couple people have recently asked me about the golden triangle. Also known as the sublime triangle, the golden triangle is an isosceles triangle in which the two longer sides have equal lengths and in which the ratio of this length to that of the third (smaller) side is the golden ratio. In the diagram on the left, the ratio of a to b is 1.618 to 1.
One exceptionally cool aspect of the golden triangle is that it can be used to form a logarithmic spiral by infinitely bisecting the segments at their phi points and drawing a spiral through their vertices:
Not surprisingly, analysts have pointed out that Da Vinci based the figure of the Mona Lisa on the golden triangle.
For more on this topic, surf around.