Octagon eight lines of reflective symmetry and rotational symmetry of order 8. A regular octagon is represented by the Schläfli symbol {8}. The internal angle at each vertex of a regular octagon is 135° (formula_1 radians). The central angle is 45° (formula_2 radians). The area of a regular octagon of side length "a" is given by In terms of the circumradius "R", the area is In terms of the apothem "r" (see also inscribed figure), the area is These last two coefficients bracket the value of pi, the area of the unit circle. The area can also be expressed as where
Williams and Stancliff Octagon Houses Williams and Stancliff Octagon Houses The Joseph Williams Octagon House and the Gilbert Stancliff Octagon House are once-identical historic mid-1850s octagon houses located next to each other at 26 and 28 Marlborough Street in Portland, Connecticut. Constructed of Portland brownstone in the 1850s, they are distinctive as the only known pair of little-altered octagon houses in the state. The pair of houses, also known as the Octagon House Pair, was added to the National Register of Historic Places in 1976. The two octagon houses are located just outside the town center of Portland, on the north side of Marlborough Street.