I am faced with the following question:
A triangulation of an n-gon is a plane graph whose infinite face boundary is a convex n-gon and all of whose other faces are triangles. How many edges does a triangulation of an n-gon have?
I have looked up pictures and understand what a triangulation of an n-gon is. I noticed that the number of edges inside the polygon is equal to the number of triangles minus 1.
Can someone help me understand how to formulate the total number of edges? (This is my first undergraduate class in graph theory, so I am looking for a simple explanation.) Thanks so much!!