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Regular heptagon
Regular polygon 7 annotated.svg
A regular heptagon
Type Regular polygon
Edges an vertices 7
Schläfli seembol {7}
Coxeter diagram CDel node 1.pngCDel 7.pngCDel node.png
Symmetry group Dihedral (D7), order 2×7
Internal angle (degrees) \approx 128.571°
Dual polygon self
Properties convex, cyclic, equilateral, isogonal, isotoxal

In geometry, a heptagon is a polygon wi seven sides an seven angles. In a regular heptagon, in which aw sides an aw angles are equal, the sides meet at an angle o 5π/7 radians, 128.5714286 degrees. Its Schläfli seembol is {7}. The aurie (A) o a regular heptagon o side length a is given bi

A = \frac{7}{4}a^2 \cot \frac{\pi}{7} \simeq 3.633912444 a^2.

The heptagon is an aa occasionally referred tae as the septagon, uisin "sept-" (an elision o septua-, a Laitin-derived numerical prefix, rather nor hepta-, a Greek-derived numerical prefix) thegither wi the Greek suffix "-agon" meanin angle).