Question

A regular octagon has a side of perimeter of 120 feet. Each side length of the octagon is increased by the same amount and now the new perimeter is 168 feet. By what amount in feet did the length of each side of the octagon increase by?

Answer 1

Explanation:

an octagon has 8 sides.

in a regular octagon all 8 sides are equally long.

the perimeter is therefore

8 × side length = 120 ft.

in fact, that tells us that the individual side length is

side length = 120/8 = 15 ft

now the new perimeter is

8 × side length new = 168 ft

side length new = 168/8 = 21 ft

so, we see that the individual side lengths increased from 15 to 21 ft and therefore by 21 - 15 = 6 ft.