Middle School

A regular pentagon is dilated by a scale factor of 73 to create a new pentagon. How does the perimeter of the new pentagon compare with the original perimeter?

Answer :

Question:

A regular pentagon is dilated by a scale factor of 7/3 to create a new pentagon. How does the perimeter of the new pentagon compare with the original perimeter?

Answer:

The perimeter of the new pentagon is equal to [tex]\frac{7}{3}[/tex] times the perimeter of the original pentagon

Solution:

If two figures are similar, then the ratio of its perimeters is equal to the scale factor

Let
,


z is the scale factor


x is the perimeter of the new pentagon


y is the perimeter of the original pentagon

Then,

Scale factor = ratio of perimeters

[tex]z=\frac{x}{y}[/tex]

In this problem we have

[tex]z=\frac{7}{3}[/tex]

Substituting we get,

[tex]\frac{7}{3} = \frac{x}{y}\\\\x = \frac{7}{3}y[/tex]

Which means,

[tex]perimeter\ of\ the\ new\ pentagon = \frac{7}{3} \times \text{ perimeter of the original pentagon}[/tex]

Therefore
, the perimeter of the new pentagon is equal to [tex]\frac{7}{3}[/tex] times the perimeter of the original pentagon