Question

The top surface of a box is in the shape of a regular octagon as shown in figure. Find the area of the octagonal surface.

Answer 1

From the figure we see that the each side of the octagon$=5cm$ and $HC=11cm$ and $AI=4cm$

Area $=Ar\left(ABCH\right)+Ar\left(GHCD\right)+Ar\left(GDEF\right)$

$=\frac{1}{2}\times 4(11+5)+5\times 11+\frac{1}{2}\times 4(11+5)$

$=(64+55){cm}^2$

$=119$ ${cm}^2$