How do you write a nonagon?

https://www.youtube.com/watch?v=iOatn50iugo What is the diagram of Nonagon?In geometry, a nonagon (/ˈnɒnəɡɒn/) or enneagon (/ˈɛniəɡɒn/) is a nine-sided polygon or 9-gon.Nonagon. Regular enneagon (nonagon) Coxeter–Dynkin diagrams...