## Heptagon

The unconstructible regular seven-sided Polygon, illustrated above, has Schläfli Symbol .

Although the regular heptagon is not a Constructible Polygon, Dixon (1991) gives several close approximations. While the Angle subtended by a side is , Dixon gives constructions containing angles of , , and .

Madachy (1979) illustrates how to construct a heptagon by folding and knotting a strip of paper.

References

Courant, R. and Robbins, H. The Regular Heptagon.'' §3.3.4 in What is Mathematics?: An Elementary Approach to Ideas and Methods, 2nd ed. Oxford, England: Oxford University Press, pp. 138-139, 1996.

Dixon, R. Mathographics. New York: Dover, pp. 35-40, 1991.

Madachy, J. S. Madachy's Mathematical Recreations. New York: Dover, pp. 59-61, 1979.