Hunter's Woods PH

Montessori Geometry

The different parts of a quadrilateral and their definitions: side, angle, vertex, base, height, diagonal, perimeter, and area.

What are the parts of a quadrilateral?

Learn about the parts of a quadrilateral, with definitions and diagrams, in this short video.

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The size of the surface covered by a quadrilateral is called its area.

Each of the line segments that form the quadrilateral’s boundaries is called a side. A quadrilateral has four sides.

• Sides that share an endpoint are called adjacent sides.
• Sides that don’t share an endpoint are called opposite sides.

The total length of the four sides is called the perimeter.

The point where two sides meet is called a vertex. A quadrilateral has four vertices.

An imaginary line joining two opposite vertices is called a diagonal.

The angle formed by two adjacent sides is called an interior angle (or, simply, an angle). A quadrilateral has four angles.

The side upon which the quadrilateral is resting is called its base.

The length of a perpendicular line from the base to the side opposite the base is called the height.

Can you now identify the parts of a quadrilateral? Reinforce your learning with the worksheet below.

Note on the Worksheets

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