Classify and Identify Polygons
Polygons
A polygon is a flat, closed plane figure made up of 3 or more sides.
Their sides meet only at their endpoints.
Polygons
NOT Polygons
These are not polygons.
Can you see the difference?
NOT Polygons
Common Types
Polygons are named for how many sides and angles they have.
Regular and Irregular Polygons
Regular polygons have sides that are all the same length.
Irregular polygons have sides of different lengths.
Regular Polygon
This polygon has 5 sides. It is called a pentagon. All of its sides are equal length, so it is a regular pentagon.
Irregular Polygon
This polygon has 5 sides. It is also a pentagon. Some of its sides are longer than others. It is an irregular pentagon.
Special Quadrilaterals
All quadrilaterals have four sides. ("Quad" means "four.")
Some quadrilaterals have special names.
They are defined by their sides (parallel or perpendicular)
and their angles (right angles or not right angles).
Let's Practice Together
Choose the answer to the questions about the figures below.
1. Is this a polygon?
yes
no
2. Is it regular?
Your Turn
3. Is this a polygon?
4. Is this a polygon?
yes
5. Is this a polygon?
yes
6. Is this polygon regular?
yes
no
7. Is this polygon regular?
yes
no
Check for Understanding
1. Match each polygon to its name.
If a polygon has more than one name... it can match to more than one word!
Answers
1. yes
2. yes
3. no
4. no
5. yes
6. no
7. yes
Check for Understanding
1.