Prove that the number of faces of a simple bipartite graph on 3 vertices is 4 faces?
The number of edges in a planar bipartite graph of order $n$ is at most $2n-4$. Proof: Let G be a planar bipartite graph with n vertices and m edges. Consider a planar embedding of $G$ . Since, $G$ is bipartite, $G$ has no cycle of length three. So, each face in the planar embedding contains at least four edges.
I tried to draw a bipartite graph where two vertices on the left connected to one vertex on the right. I can conclude that I have 3 faces, but the correct answer should be 4.