I have this graph
now i should check if this graph can be planar.
v - number of vertices
e - number of edges
f - number of faces
So it's hold the theorem "If v ≥ 3 then e ≤ 3v − 6 "
v = 9, e = 15
15 ≤ 21
and should hold v - e + f = 2 from here f = 2 - v + e = 2 - 9 + 15 = 8
so f = 8 now my question is how to easily count faces (regions bounded by edges, including the outer, infinitely large region) of the graph??