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Quadrilateral Classification

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How to Classify Quadrilaterals, a selection of answers from the Dr. Math archives.

Quadrilateral Classification: Definition of a Trapezoid
What is the correct definition of a trapezoid, and why?

Inclusive vs. Exclusive Definitions
My geometry teacher says that a square is not also a rhombus, a rectangle, and a parallelogram. Please help!

Inclusive and Exclusive Definitions
Are squares rectangles? Are rectangles squares?

The Six Quadrilaterals
My daughter forgot her textbook and needs to know the six types of quadrilaterals.

What is 4-sided and has no equal angles?

Is a Square a Rectangle?
Are squares rectangles? What is a pentagon?

Is a Square a Rhombus?
I've come across different definitions of a "rhombus" that make it unclear whether a square is a rhombus.

Describing a Rhombus
What is a rhombus?

Rhombus vs. Rhomboid
What is the difference between a rhombus and a rhomboid?

Proving Quadrilateral is a Parallelogram
We are having a problem with the idea of a quadrilateral having one pair of opposite sides congruent and one pair of opposite angles congruent.

For definitions and diagrams, see:

Quadrilateral Formulas - Dr. Math Geometric Formulas FAQ
Return to
Middle School School Triangles/Polygons
High School Triangles/Polygons
Index of Selected Answers to Common Questions

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