en.wikipedia.org/wiki/Quadrilateral

Some types of quadrilaterals. Edges and vertices, 4. Schläfli symbol, {4} (for
square). Area, various methods; see below. Internal angle (degrees), 90° (for
square and rectangle). In Eucli...

www.mathsisfun.com/quadrilaterals.html

A Quadrilateral has four-sides, it is 2-dimensional (a flat shape), closed (the lines
... Some types are also included in the definition of other types! ... Other Names.

www.montereyinstitute.org/courses/DevelopmentalMath/COURSE_TEXT2_RESOURCE/U07_L2_T1_text_final.html

Picking apart the name “quadrilateral” helps you understand what it refers to. The
prefix ... A quadrilateral also has four angles formed by its four sides. Below ...
The other special case of a parallelogram is a special type of rectangle, a square.

www.math-only-math.com/different-types-of-quadrilaterals.html

Different types of quadrilaterals are explained with their definition and properties
along with the diagram. Parallelogram A quadrilateral is called a parallelogram.

www.reference.com/math/quadrilateral-parallelogram-5f25e29d0bf71259

A quadrilateral is a two-dimensional shape with four straight sides, although ...
names; for instance, a shape that has four unequal sides is a quadrilateral but not
a parallelogram. ... The basic four types of quadrilaterals are squares, rectangles,
...

thinkmath.edc.org/resource/shape-quadrilateral

A quadrilateral is a polygon that has exactly four sides. ... Just as triangles and
quadrilaterals are special types of polygons, there are many subclasses of ... The
square is also the name of the regular quadrilateral -- one in which all sides are ...

www.math.com/school/subject3/lessons/S3U2L3DP.html

There are many different kinds of quadrilaterals, but all have several things in
common: all of them have four sides, are coplanar, have ... A rectangle has two
pairs of opposite sides parallel, and four right angles. ... (British name: Trapezium
).

www.cut-the-knot.org/Curriculum/Geometry/Quadrilaterals.shtml

Quadrilateral is a geometric shape that consists of four points (vertices)
sequentially ... summarize the relationship between various kinds of
quadrilaterals: ... Here is a list of all the properties of quadrilaterals that we have
mentioned along with ...

study.com/academy/lesson/what-is-a-quadrilateral-definition-properties-types-example.html

We name each vertex with a capital letter. Let's name our quadrilateral with the
four vertices: P, N, C, and L. It also has four sides: the segments PN, NC, CL, and
...

www.khanacademy.org/math/basic-geo/basic-geo-shapes/basic-geo-classifying-shapes/e/quadrilateral_types

Identify quadrilaterals based on pictures or attributes. ... Quadrilateral types ... All
squares have four right angles and four sides that are equal in length. Which of ...