Octagon Formula Side Length. A = 2 * a² * ( 1 + √2 ) rc= a / 2 * √4 + 2 * √2. If you label “a” as the length of one side of an octagon, then the sides of the large square are \(a\sqrt{2}+1\).
Area of an octagon = \(2a^{2}(1+\sqrt{2})\) where ‘a’ is the length of any one side of the octagon. The formula for perimeter of an octagon is given by: $$perimeter = s * 8$$ octagon side length
As we know that perimeter is simply the sum of all eight sides.
(htmlhelp version requires that internet explorer v4 or greater be present.) Perimeter = length of 8 sides. My equation is as follows, (a/√2)*2+a=b, or a over radical 2, times 2, plus a, equals b. Area of an octagon = \(2a^{2}(1+\sqrt{2})\) where ‘a’ is the length of any one side of the octagon.