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2015-11-27T14:03:21+05:30
In Euclidean plane geometry, a quadrilateral is a polygon with four edges (or sides) and four vertices or corners. Sometimes, the term quadrangle is used, by analogy with triangle, and sometimes tetragon for consistency withpentagon (5-sided), hexagon (6-sided) and so on.The origin of the word "quadrilateral" is the two Latin words quadri, a variant of four, and latus, meaning "side".Quadrilaterals are simple (not self-intersecting) or complex (self-intersecting), also called crossed. Simple quadrilaterals are either convex or concave.The interior angles of a simple (and planar) quadrilateral ABCD add up to 360 degrees of arc, that isThis is a special case of the n-gon interior angle sum formula (n − 2) × 180°.All convex quadrilaterals tile the plane by repeated rotation around the midpoints of their edges.
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