In the mathematical field of graph theory, the triangle graph is a planar undirected graph with 3 vertices and 3 edges, in the form of a triangle.[1]
The triangle graph is also known as the cycle graph C 3 {\displaystyle C_{3}} and the complete graph K 3 {\displaystyle K_{3}} .
The triangle graph has chromatic number 3, chromatic index 3, radius 1, diameter 1 and girth 3. It is also a 2-vertex-connected graph and a 2-edge-connected graph.
Its chromatic polynomial is ( x − 2 ) ( x − 1 ) x . {\displaystyle (x-2)(x-1)x.}