The LessonA paralleogram is a four sided shape with opposite sides parallel and equal in length.
Dictionary DefinitionThe Oxford English Dictionary defines a parallelogram as "a four-sided plane rectilinear figure whose opposite sides are parallel; especially one whose sides do not intersect at right angles."
Properties of Parallelograms
Opposite sides of a parallelogram are parallel.
Opposite sides of a parallelogram are of equal length.
Opposite angles of a parallelogram are equal.
Adjacent angles of a parallelogram add up to 180°. They are supplementary angles.
All angles of a parallelogram add up to 360°.
The diagonals of a parallelogram bisect each other. The diagonals cross each other half-way along their lengths.
The Perimeter of a ParallelogramThe perimeter of a parallelogram is given by the formula:
In this formula, b is the length of the base and s is the length of the side of the parallelogram.
The Area of a ParallelogramThe area of a parallelogram is given by the formula:
In this formula, b is the length of the base and h is the height of the parallelogram.
Read more about how to find the area of a parallelogram
Interactive WidgetHere is an interactive widget to help you learn about parallelograms.
What's in a Name?Parallelogram comes from the Greek word "parallelogrammon" meaning 'parallel sides'.
A Parallelogram is a PolygonA parallelogram is a type of polygon. A polygon is a 2-dimensional shape with straight sides. A parallelogram is an irregular polygon. Irregular polygons have different length sides and different angles.
A Parallelogram Is a QuadrilateralA parallelogram is a quadrilateral. A quadrilateral is a four-sided polygon. Squares, rectangles and trapezoids are also quadrilaterals.
Interior Angles of a ParallelogramA parallelogram is a four-sided polygon. The sum of the interior angles of an n-sided polygon is is:
(n − 2) × 180°This means the interior angles of a quadrilateral (where n = 4) add up to:
(4 − 2) × 180° = 360°This is the case for all quadrilaterals, such as squares, rectangles and trapezoids.