Answer:
Below in bold.
Explanation:
The angle in a regular octagon = 180 - (360/8) = 135.
Using trigonometry sin (135/2) = k/2 / EF
sin 67.5 = k / 2EF
2EF = k / sin 67.5
EF = k / 2 sin 67.5 = k/1.8478
Perimeter of octagon = 8 * k/1.8478
= 4.33k to the nearest hundredth.