411 REFERENCE · Wikibooks
Geometry/Parallelograms
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
Parallelograms
A parallelogram is a geometric figure with two
pairs of parallel sides. Parallelograms are a special type of quadrilateral.
The opposite sides are equal in length and the opposite angles are also equal.
The area is equal to the product of any side and the distance between that
side and the line containing the opposite side.
Parallelogram
Properties of Parallelograms
The following properties are common to all parallelograms (parallelogram, rhombus, rectangle, square)
both pairs of opposite sides are parallel
both pairs of opposite sides are congruent
both pairs of opposite angles are congruent
the diagonals bisect each other
consecutive angles are supplementary
Special Parallelograms
Rhombus
A rhombus is a parallelogram with four congruent sides.
The diagonals of a rhombus are perpendicular.
Each diagonal of a rhombus bisects two angles the rhombus.
A rhombus may or may not be a square.
Rhombus
Square
A square is a parallelogram with four right angles and four congruent sides.
A square is both a rectangle and a rhombus and inherits all of their properties.
Square