1. Section 6-1 Polygons

2. Polygon Formed by three or more segments called sides. No two sides with a common endpoint are collinear. Each side intersects exactly two other sides, one at each endpoint.

3. Each endpoint of a side is a vertex of a polygon. Polygons are named by listing the vertices consecutively.

4. Examples of Polygons:

5. These are not Polygons:

6. Must have at least 3 sides to form a polygon.

7. Polygons are classified according to the number of sides they have. Number of SidesName 3Triangle 4Quadrilateral 5Pentagon 6Hexagon 7Heptagon 8Octagon 9Nonagon 10Decagon 12Dodecagon nn-gon

8. Two Types of Polygons: 1.Convex: If a line was extended from the sides of a polygon, it will NOT go through the interior of the polygon. Example:

9. 2. Concave: If a line was extended from the sides of a polygon, it WILL go through the interior of the polygon. Example:

10. Regular Polygon A polygon that is equilateral and equiangular. –E–Equilateral: all of its sides are congruent –E–Equiangular: all of its angles are congruent

12. Diagonal A segment joining two nonconsecutive vertices *The diagonals are indicated with dashed lines.

13. Interior Angles of a Quadrilateral Theorem The sum of the measures of the interior angles of a quadrilateral is 360 degrees. 1 4 2 3