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Octagon

From AoPSWiki

An octagon is an eight-sided polygon.

Regular octagons

Each internal angle of a regular octagon measures 135 degrees, so the sum of the angles is 1080^{\circ}.

Area: 2s^2(1 + \sqrt{2})

Apothem: \frac{s(1+ \sqrt2 )}{2}

Inradius: \frac{s(1+ \sqrt2 )}{2}

Circumradius: \frac{s\sqrt{4+2\sqrt{2}}}{2}


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