Use Euler's formula to find the missing number.

Vertices: 23
Edges: 39
Face: ?

1 answer

Using Euler's formula:

F + V - E = 2

where F is the number of faces, V is the number of vertices, and E is the number of edges.

Plugging in the given values:

F + 23 - 39 = 2

Simplifying:

F - 16 = 2

Adding 16 to both sides:

F = 18

Therefore, the missing number is 18.