Hexagon Hexagon In geometry, a hexagon (from Greek ἕξ "hex", "six" and γωνία, "gonía", "corner, angle") is a six-sided polygon or 6-gon. The total of the internal angles of any simple (non-self-intersecting) hexagon is 720°. A "regular hexagon" has Schläfli symbol {1} and can also be constructed as a truncated equilateral triangle, t{3}, which alternates two types of edges. A regular hexagon is defined as a hexagon that is both equilateral and equiangular. It is bicentric, meaning that it is both cyclic (has a circumscribed circle) and tangential (has an inscribed circle). The common length of the sides equals the radius
Real projective plane of the (equivalent) ordinary disk are identified with each other; this is how a real projective plane is formed out of a disk. Therefore the surface shown in Figure 1 (cross-cap with disk) is topologically equivalent to the real projective plane "RP". The points in the plane can be represented by homogeneous coordinates. A point has homogeneous coordinates ["x" : "y" : "z"], where the coordinates ["x" : "y" : "z"] and ["tx" : "ty" : "tz"] are considered to represent the same point, for all nonzero values of "t". The points with coordinates ["x" : "y" : 1] are