Linked from

The 12 pages that link to Quadrilateral, each with the reason it gives.

• Cyclic quadrilateralNarrower topic: Cyclicity adds a circle condition to this broader polygon class.

• Ptolemy's theoremNarrower topic: The theorem concerns a particular class of quadrilaterals with four vertices on a circle.

• RectangleNarrower topic: A rectangle is a quadrilateral whose four angles are right angles.

• SquareNarrower topic: A square is a quadrilateral with additional constraints on its sides and angles.

• ParallelogramNarrower topic: A parallelogram is a quadrilateral with the additional condition that both pairs of opposite sides are parallel.

• Brahmagupta's formulaNarrower topic: The formula concerns the area of this four-sided figure.

• Ptolemy's inequalityNarrower topic: The inequality compares the four side lengths and two diagonals of this figure.

• Bretschneider's formulaNarrower topic: The formula applies to this entire polygon family, not only rectangles or cyclic cases.

• Van Aubel's theoremNarrower topic: The theorem applies to squares constructed on the sides of this four-sided figure.

• Euler's quadrilateral theoremNarrower topic: The theorem applies to every quadrilateral, without requiring convexity or parallel sides.

• Pitot theoremNarrower topic: The theorem compares the two pairs of opposite sides of this polygon.