Tangential quadrilateral all of whose sides are tangent to a single conic section has three diagonals that meet at a point. From a tangential quadrilateral, one can form a hexagon with two 180° angles, by placing two new vertices at two opposite points of tangency; all six of the sides of this hexagon lie on lines tangent to the inscribed circle, so its diagonals meet at a point. But two of these diagonals are the same as the diagonals of the tangential quadrilateral, and the third diagonal of the hexagon is the line through two opposite points of tangency. Repeating this same
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.