A polygon vertex of a simple polygon is a principal polygon vertex if the diagonal intersects the boundary of only at and .
Principal Vertex
See also
Ear, MouthExplore with Wolfram|Alpha
References
Meisters, G. H. "Polygons Have Ears." Amer. Math. Monthly 82, 648-751, 1975.Meisters, G. H. "Principal Vertices, Exposed Points, and Ears." Amer. Math. Monthly 87, 284-285, 1980.Toussaint, G. "Anthropomorphic Polygons." Amer. Math. Monthly 98, 31-35, 1991.Referenced on Wolfram|Alpha
Principal VertexCite this as:
Weisstein, Eric W. "Principal Vertex." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/PrincipalVertex.html