Pareal
Pareal by TheFemThemGhoulMormer January 10, 2026
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Parallelogram
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. The three-dimensional counterpart of a parallelogram is a parallelepiped.
The etymology (in Greek παραλληλ-όγραμμον, a shape "of parallel lines") reflects the definition.
A simple (non self-intersecting) quadrilateral is a parallelogram if and only if any one of the following statements is true:12
Two pairs of opposite sides are equal in length.
Two pairs of opposite angles are equal in measure.
The diagonals bisect each other.
One pair of opposite sides are parallel and equal in length.
Adjacent angles are supplementary.
Each diagonal divides the quadrilateral into two congruent triangles.
The sum of the squares of the sides equals the sum of the squares of the diagonals. (This is the parallelogram law.)
It has rotational symmetry of order 2.
The etymology (in Greek παραλληλ-όγραμμον, a shape "of parallel lines") reflects the definition.
A simple (non self-intersecting) quadrilateral is a parallelogram if and only if any one of the following statements is true:12
Two pairs of opposite sides are equal in length.
Two pairs of opposite angles are equal in measure.
The diagonals bisect each other.
One pair of opposite sides are parallel and equal in length.
Adjacent angles are supplementary.
Each diagonal divides the quadrilateral into two congruent triangles.
The sum of the squares of the sides equals the sum of the squares of the diagonals. (This is the parallelogram law.)
It has rotational symmetry of order 2.
What are you studying Jane?
Oh, I am studying quadrilaterals, specifically I am on Chapter 5 proving a quadrilateral is a Parallelogram, Claire.
Oh, I am studying quadrilaterals, specifically I am on Chapter 5 proving a quadrilateral is a Parallelogram, Claire.
Parallelogram by david faustino December 18, 2012
Related Words
Pareal • paralyzer • parallel • parallelogram • parallel parking • paralyzed • Parallax • parallel park • paralegal • paraletic
Celebration Parallax
The phenomenon whereby the exact same set of facts is either celebrated or deplored depending solely on the political bias of the observer.
When a liberal writes that increased immigration is good because it leads to a liberal demographic shift, but then writes that conservatives decrying increased immigration are pushing "replacement theory," that's celebration parallax.
Celebration Parallax by sensei10 January 31, 2023
feline paralysis
The inability to move or accomplish anything useful because the cat is lying in you lab purring/sleeping.
Him: Hon, could you grab me a beer from the fridge?
Her: Get it yourself!
Him: I can't. I've got feline paralysis.
Her: Get it yourself!
Him: I can't. I've got feline paralysis.
feline paralysis by metasymantic February 6, 2009
parallel swizzle
parallel swizzle by intellectualbadass October 21, 2013