College

How many vertices does a regular pyramid with 40 edges have?

Use Euler's formula: [tex]V + F = E + 2[/tex].

A. 20
B. 21
C. 40
D. 42

Answer :

To solve the problem of determining the number of vertices in a regular pyramid with 40 edges, we can use Euler's formula, which is:

[tex]\[ V + F = E + 2 \][/tex]

where:
- [tex]\( V \)[/tex] is the number of vertices,
- [tex]\( F \)[/tex] is the number of faces,
- [tex]\( E \)[/tex] is the number of edges.

According to the problem, the number of vertices in the pyramid is equal to the number of faces, so we have:

[tex]\[ V = F \][/tex]

We are also given that the number of edges [tex]\( E \)[/tex] is 40.

Using these pieces of information, let's substitute into Euler's formula:

[tex]\[ V + F = E + 2 \][/tex]
[tex]\[ V + V = 40 + 2 \][/tex]
[tex]\[ 2V = 42 \][/tex]

Solve for [tex]\( V \)[/tex]:

[tex]\[ V = \frac{42}{2} \][/tex]
[tex]\[ V = 21 \][/tex]

Therefore, the number of vertices in the pyramid is 21.