A regular octagon has side length 10.9 in. The perimeter of the octagon is 87.2 in cm and the area is 392.4 in2. A second octagon has side lengths equal to 21.8 in. Find the perimeter of the second octagon. Round to the nearest hundredth.(Points : 3)

Question

directrix · Answer

Is the second octagon regular? Although the question does not specifiy that, I assume the second octagon is regular because of the statement "has side lengths equal to 21.8 in."

directrix · Answer

Any two regular octagons are similar.

The ratio of the sides (scale factor) is the same as the ratio of the perimeters.

directrix · Answer

10.9 / 21.8 = 87.2 / p where p is the perimeter of the second octagon.

directrix · Answer

10.9 / 21.8 = 87.2 / p

Cross multiply to get:

10.9 * p = (87.2)*(21.8)

What do you get when you solve for p?  --- @Brandon_hockinson