Question

Question 7
Using Euler's formula, find the unknown:
$\begin{array}{cccc}Faces& ?& 5& 20\\ Vertices& 6& ?& 12\\ Edges& 12& 9& ?\end{array}$

Answer 1

By euler’s formula, we have
F + V - V = 2
i) F + 6 – 12 = 2
F = 2 + 6
F = 8
ii) 5 + V – 9 = 2
V-4 = 2
V = 6
iii) 20 + 12 – E = 2
32 – E = 2
E = 30