What is the area of an octagon with a radius of 8?

Answer 1

Radii are related to circles.

What do you mean by an "...octagon with a radius..."?

Unless the octagon is regular it is impossible to to calculate the area of the octagon from one measurement alone.

So assuming that the octagon is a regular octagon, what do you mean by radius? Do you mean:

• the radius of the circumcircle which passes through all vertices

area regular octagon = 8 × ½ × 8 × 8 × sin(360°/8) units²

= 256 × sin(45) units²

= 256 × 1/√2 units²

= 128√2 units²

≈ 181 units²

• the radius of the inscribed circle, which is the apothem of the octagon

area regular octagon = 8 × 8 × 8 × tan((360°/8)/2) units²

≈ 196 units²

• Something else

Re-ask your question explaining what you mean by "radius".

Answer 2

80