Question

Find the area of a regular octagon with apothem K and side of 10.
40K
60K
80K

Answer 1

For a regular octagon the area is given by \[8 × \text {Apothem}^2 × \tan(π/8) \]

Again,

\[\text{Side} = 2 × \text{ Apothem } × \tan(π/8) \]

So use the second one to find the value of tan(π/8) and then substitute the value in the first which will give 40k as answer.