Take 10 golden triangles, arrange them with their sharp points touching, and you have a golden decagon, fitting perfectly within the iris of the eye, vertices neatly touching the rim.

画10三角，把它们的顶点挨着排好，然后你就得出十形，与瞳孔中的虹膜完美地致，十形的最早点正好在眼眶。