A plane figure consisting of four points, each of which is joined to two other points by a line segment (where the line segments may intersect). A quadrangle may therefore be concave or convex; if it is convex, it is called a quadrilateral.
Quadrangle
See also
Complete Quadrangle, Cyclic Quadrangle, Quadrilateral, TetrastigmExplore with Wolfram|Alpha
References
Coxeter, H. S. M. and Greitzer, S. L. "Collinearity and Concurrence." Ch. 3 in Geometry Revisited. Washington, DC: Math. Assoc. Amer., pp. 51-79, 1967.Durell, C. V. "The Quadrilateral and Quadrangle." Ch. 7 in Modern Geometry: The Straight Line and Circle. London: Macmillan, pp. 77-87, 1928.Referenced on Wolfram|Alpha
QuadrangleCite this as:
Weisstein, Eric W. "Quadrangle." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Quadrangle.html