Examples include the regular pentagon, heptagon, and nonagon and the equilateral triangular bipyramid. Like the 50p coin, it is an equilateral curve heptagon. A heptagonal number is a figurate number that represents a heptagon. In geometry, a heptagon is a seven-sided polygon or 7-gon. Thus its sides coincide with one side and two particular diagonals of the regular heptagon. In general, a heptagram is any self-intersecting heptagon (7-sided polygon). The 1000 Kwacha coin of Zambia is a true heptagon. The Brazilian 25-cent coin has a heptagon inscribed in the coin's disk. Then formula 11 gives an approximation for the edge of the heptagon. Instead, she had a heptagon as her chest symbol. The linear interpolation in such cases will produce a plausible single heptagon. Blue, {7/2} and green {7/3} star heptagons inside a red heptagon. From each collar hangs a white heptagon symbolic of the united seven authorities. The military headquarters of the Confederation in Fargo, North Dakota is called the "Heptagon". The "regular heptagon" belongs to the D point group (Schoenflies notation), order 28.