Rectangular pizza stone

On this Wikipedia the language links are at the top of the page across from the article title. In Euclidean plane geometry, a rectangle is a quadrilateral rectangular pizza stone four right angles.

Rectangles are involved in many tiling problems, such as tiling the plane by rectangles or tiling a rectangle by polygons. A rectangle is a special case of both parallelogram and trapezoid. A square is a special case of a rectangle. A rectangle is a special case of a parallelogram in which each pair of adjacent sides is perpendicular. A trapezium is a convex quadrilateral which has at least one pair of parallel opposite sides. Simple: The boundary does not cross itself. Star-shaped: The whole interior is visible from a single point, without crossing any edge.

De Villiers defines a rectangle more generally as any quadrilateral with axes of symmetry through each pair of opposite sides. This definition includes both right-angled rectangles and crossed rectangles. Quadrilaterals with two axes of symmetry, each through a pair of opposite sides, belong to the larger class of quadrilaterals with at least one axis of symmetry through a pair of opposite sides. A rectangle is cyclic: all corners lie on a single circle. It is isogonal or vertex-transitive: all corners lie within the same symmetry orbit. The dual polygon of a rectangle is a rhombus, as shown in the table below.