Solution-
As we know the area of the regular octagon with side as a is,
Area = 2(1+√2)a²
Here the area given as 9.68√2 + 9.68 = 23.36
Equating both
⇒2(1+√2)a² = 23.36
⇒2×2.41×a² = 23.36
⇒a² = 23.36/4.82 = 4.84
⇒a = 2.2meter
Therefore the length of the side of the given octagon is 2.2 meter