parallelogram

parallelogram,

closed plane figure bounded by four line segments, or sides, with opposite pairs of sides parallel and equal in length. The rhombus, rectangle, and square are special types of parallelograms. Any side of a parallelogram is a base; an altitude is the perpendicular distance from a base to the opposite parallel side. The area of a parallelogram is equal to the product of the lengths of its base and altitude. The diagonals of a parallelogram, connecting opposite vertices, bisect one another; either diagonal divides the parallelogram into two congruent triangles.

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Parallelogram

A quadrilateral having both pairs of the opposite sides parallel to each other.

Illustrated Dictionary of Architecture Copyright © 2012, 2002, 1998 by The McGraw-Hill Companies, Inc. All rights reserved

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Parallelogram

 

a quadrangle whose opposite sides are parallel (see Figure 1). A parallelogram can also be defined as a convex quadrangle that satisfies any of the following conditions: (1) both pairs of opposite sides consist of equal line segments; (2) one pair of opposite sides consists of equal and parallel segments;

Figure 1

(3) each pair of opposite vertices has equal angles; or (4) the diagonals’ point of intersection bisects each diagonal. Figure 1 illustrates different types of parallelograms, including the rectangle (Figure 1,b), a parallelogram whose angles are right angles; the rhombus (Figure l,c), an equilateral parallelogram; and a square (Figure 1,d), an equilateral rectangle.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

parallelogram

[‚par·ə′lel·ə‚gram]

(mathematics)

A four-sided polygon with each pair of opposite sides parallel.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

parallelogram

a quadrilateral whose opposite sides are parallel and equal in length

Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005