Using Euler’s formula find the unknown
Faces | ? | 5 | 20 |
Vertices | 6 | ? | 12 |
Edges | 12 | 9 | ? |
By Euler's formula, we have
F + V - E = 2
(i) F + 6 - 12 = 2
F - 6 = 2
F = 8
(ii) 5 + V - 9 = 2
V - 4 = 2
V = 6
(iii) 20 + 12 - E = 2
32 - E = 2
E = 30
Thus, the table can be completed as:
Faces | 8 | 5 | 20 |
Vertices | 6 | 6 | 12 |
Edges | 12 | 9 | 30 |