Geometry/Parallelograms

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.

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

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.



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.