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In geometry, an equilateral polygon is a polygon which has all sides of the same length.
For instance, an equilateral triangle is a triangle of equal edge lengths. All equilateral triangles are similar to each other, and have 60 degree internal angles.
An equilateral quadrilateral is a rhombus, which includes the square as a special case.
An equilateral polygon which is cyclic (its vertices are on a circle) is a regular polygon (a polygon that is both equilateral and equiangular).
All equilateral quadrilaterals are convex, but concave equilateral pentagons exist, as do concave equilateral polygons with any larger number of sides.
Viviani's theorem generalizes to equilateral polygons.
Triambi, which are equilateral hexagons with trigonal symmetry, appear in the three triambic icosahedra:
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