Question

Use Euler’s Formula to find the missing number.

edges:49
faces:21
vertices:?

30
32
26
28

Answer 1

it is 30, 30 - 49 is -19 plus 21 is 2

Answer 2

Option 1st is correct

number of vertices = 30

Explanation:

Let e be the number of edges, f be the number of faces and v be the number of vertices.

As per the statement:

Number of edges(e) = 49

Number of faces(f) = 21

We have to find number of vertices.

using Euler's formula:

`v-e+f = 2`

then;

`v-49+21=2`

⇒
`v-28=2`

Add 28 to both sides we have;

`v = 30`

Therefore, the number of vertices = 30