1. Polygons

2. A Polygon is a closed plane figure formed by line segments.
open
Not a polygon

3. Polygons are named by the number of sides or angles they have
Polygons are named by the number of sides or angles they have. The number of sides is equal to the number of angles.

4. Name #Sides #Angles Examples
Triangle
Quadrilateral
Pentagon

6. Polygons are either regular or irregular. These are regular polygons:
These are irregular
polygons:

7. A regular polygon has all sides the same length and all the angles the same measure.

8. An irregular polygon has sides of various lengths and angles of different measures.

9. Polygons that have the same shape and size are congruent.
Exact fit

10. Polygons that have the same shape are similar
Polygons that have the same shape are similar. They may or may not have the same size.
Similar polygons
Non-Similar polygons