Identify and Classify Polygons

Polygons

A polygon is a closed figure that has three or more sides.  Each side is a line segment, and the sides meet only at their endpoints.

Examples

Not Polygons

Figures that are not polygons have curved sides, crossing lines, or are not closed. 

Examples

Naming Polygons

The most basic way to identify or name a polygon is by the number of sides it has.

Examples

Regular Polygons

A regular polygon is a polygon whose sides are all the same length.  Its angles are also congruent (all the same measure).

Irregular Polygons

An irregular polygon has sides and angles of varying sizes.

Examples

Can you identify the regular and irregular polygons below?

Quadrilaterals

A quadrilateral is a four-sided figure.

The sum of the angle measures in a quadrilateral is 360 degrees (360^o).

There are many different kinds of quadrilaterals.

You can use sides and angles to classify them.

Examples

Practice

Classify each polygon in as many ways as you can.

1.

2.

3.

4.

5.

6.

Use the descriptions of quadrilaterals to answer each question.

7.  Is a square a rectangle?

8.  Is a rectangle a square?

9.  Is a parallelogram a trapezoid?

10.  Is a rhombus a parallelogram?

11.  Is a rectangle a rhombus?

12.  Is a square a rhombus?

Answers

1.  quadrilateral, parallelogram, rectangle

2.  quadrilateral, trapezoid

3.  regular octagon

4.  quadrilateral

5.  regular pentagon

6.  quadrilateral, parallelogram

7.  Yes

8.  No

9.  No

10.  Yes

11.  No

12.  Yes