decagon

decagon

1. how many diagonals are there is a decagon?????

一个十角形中有多少条对角线？

2. regular decagon

正十边形

3. 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个金三角，把它们的顶点挨着排好，然后你就得出一个金十边形，与瞳孔中的虹膜完美地一致，十边形的最早点正好在眼眶。