Equilateral polygon with 60° internal angles. An equilateral quadrilateral is called a rhombus, an isotoxal polygon described by an angle α. It includes the square as a special case. A convex equilateral pentagon can be described by two angles α and β, which together determine the other angles. Concave equilateral pentagons exist, as do concave equilateral polygons with any larger number of sides. An equilateral polygon which is cyclic (its vertices are on a circle) is a regular polygon (a polygon that is both equilateral and equiangular). A tangential polygon (one that has an incircle tangent to all its sides) is equilateral
Winter Triangle Winter Triangle The Winter Triangle is an astronomical asterism formed from three of the brightest stars in the winter sky. It is an imaginary equilateral triangle drawn on the celestial sphere, with its defining vertices at Sirius, Betelgeuse, and Procyon, the primary stars in the three constellations of Canis Major, Orion, and Canis Minor, respectively. For much of the night in the northern winter, the Winter Triangle lies high in the sky at mid-northern latitudes, but can also be seen during autumn in the early morning to the East. In the spring the winter triangle is visible early in the