In an undirected connected planar graph G, there are eight vertices and five faces. The number of edges in G is ___.

Question

Accepted Answer

E = 11 Euler's formula for connected planar graphs states V - E + F = 2, where V is the number of vertices, E is the number of edges, and F is the number of faces (including the unbounded outer face). With V and F both known, we can solve directly for E by simple algebra.