# Parallelogram

A parallelogram is a quadrilateral with opposite sides parallel and therefore opposite angles equal.

Parallelogram is an elementary-school-level concept. It is listed in the California State Standards for Grade 3.

### Examples

Rectangle: | A rectangle is a quadrilateral with opposite sides of equal length and with four right angles. |

Square: | A square is a polygon with four sides of equal length and at right angles to each other. |

### Prerequisites

Angle: | An angle is a measure of the amount of rotation about the point of intersection of two lines or line segments that is required to bring one into correspondence with the other. |

Parallel: | In two-dimensional Euclidean space, two lines that do not intersect are said to be parallel. In three-dimensional Euclidean space, parallel lines not only fail to intersect, but also maintain a constant separation between points closest to each other on the two lines. |

Polygon: | A polygon is a two-dimensional figure that consists of a collection of line segments, joined at their ends. |