In Euclidean geometry, a parallelogram is a simple (non self-intersecting) quadrilateral with two pairs of parallel sides. The opposite or facing sides of a parallelogram are of equal length and the opposite angles of a parallelogram are of equal measure. The congruence of opposite sides and opposite angles is a direct consequence of the Euclidean Parallel Postulate and neither condition can be proven without appealing to the Euclidean Parallel Postulate or one of its equivalent formulations.
A simple (non self-intersecting) quadrilateral is a parallelogram if and only if any one of the following statements is true;
Two pairs of opposite sides are equal in length
One pair of opposite sides are parallel and equal in length.
source:From Wikipedia, the free encyclopedia;Subject: Parallelogram.
square
A square, rectangle, or quadrilateral
rhombus (although the angles can technically be right angles as well)
A rhombus. A square is one special rhombus with right angles.
triangle
A four-sided figure with two pairs of parallel sides the same length and four right angles is called a square.
Square
square
A quadrilateral with 4 right angles and opposite sides that are parallel can be either a rectangle if the adjacent sides are of different length or a square if the adjacent sides are of the same length.
A square, rectangle, or quadrilateral
rhombus (although the angles can technically be right angles as well)
A rhombus. A square is one special rhombus with right angles.
triangle
irregular trapezoid
You are a rhombus.
triangle
A rhombus