Find the area of this regular octagon Round to the nearest t

Find the area of this regular octagon. Round to the nearest tenth. Area is m^2 Insert answer in blank above!!

Solution

there are a total of 16 similar triangles in the octagon as shown in diagram.

area of one triangle = 0.5 x 10cos(360/16) x 10sin(360/16)

= 17.67767 m²

area of octagon = 16 x 17.67767 = 282.843 m²