1. Polygon Definition: A closed figure.
How to Name: All capital letters. Use as many letter as sides to the polygon.
Some Examples:

2. Diagonal
Definition: a line segment drawn from one vertex to another in a polygon.
Picture:

3. Concave
Definition: Polygon dips inward (Some diagonals can be drawn outside the shape).
Picture:

4. Convex
Definition: Polygon only points outward. (No diagonals can be drawn outside the shape).
Picture:

5. Convex or Concave?

6. Regular Polygon
Definition: A closed figure, with congruent sides and congruent angles.
Picture: All sides and angles marked congruent.

7. Regular Polygons

8. Perimeter Definition: Sum of the lengths of the sides.
Picture: Perimeter = 26cm