Hexagon circle) with vertices given by the six intersections of the edges of a triangle and the three lines that are parallel to the edges that pass through its symmedian point. If the successive sides of a cyclic hexagon are "a", "b", "c", "d", "e", "f", then the three main diagonals intersect in a single point if and only if . If, for each side of a cyclic hexagon, the adjacent sides are extended to their intersection, forming a triangle exterior to the given side, then the segments connecting the circumcenters of opposite triangles are concurrent. If a hexagon has vertices
Magic hexagon can be called a T-hexagon and it has many more properties than the hexagon of hexagons. As with the above, the rows of triangles run in three directions and there are 24 triangles in a T-hexagon of order 2. In general, a T-hexagon of order "n" has formula_10 triangles. The sum of all these numbers is given by: If we try to construct a magic T-hexagon of side "n", we have to choose "n" to be even, because there are rows so the sum in each row must be For this to be an integer, "n" has to be even.