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In geometry, an octagon is a polygon that has eight sides. In some parts of the world, stop signs are in the shape of a regular octagon.
Regular octagons A regular octagon is an octagon whose sides are all the same length and whose internal angles are all the same size. The internal angle at each vertex of a regular octagon is 135°. The area of a regular octagon of side length a is given by In terms of , the area is In terms of , the area is Construction An octagon is constructible with compass and straightedge. To do so, follow steps 1 through 18 of the animation, noting that the compass radius is not altered during steps 7 though 10. See also | ||||||||
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