1. Name the polygons with the following number of sides: 3 4 5 6 7 8 9 10 12 Triangle Quadrilateral Pentagon Hexagon Heptagon Octagon Nonagon Decagon Dodecagon

2. Polygons Geometry Mr. Zampetti Unit 3, Day 2

3. Today’s Objectives To learn how to classify polygons To learn how to find the sum of the measures of the interior and exterior angles of a polygon

4. Definition Polygon: a closed plane figure with at least three sides.

5. Video: Polygons in Architecture

6. Without the use of your notes: Matching names with number of sides: http://www.quia.com/cm/86645.html?AP _rand=2098901149 http://www.quia.com/cm/86645.html?AP _rand=2098901149 Concentration game: http://www.quia.com/jg/1507267.html http://www.quia.com/jg/1507267.html

7. Definition Convex: a polygon is convex if no diagonal contains points outside the polygon. http://img.sparknotes.com/figures/B/b333d91dce2882b2db48b8ad670cd15a/convexconcave.gif

8. Definition Concave: a polygon is concave if a diagonal contains points outside the polygon. http://img.sparknotes.com/figures/B/b333d91dce2882b2db48b8ad670cd15a/convexconcave.gif

9. Theorem 2-3: Polygon Interior Angle-Sum Theorem The sum of the measures of the interior angles of an n-gon is (n - 2)180.

10. Practice Find the sum of the measure of the interior angle of the following polygons: –15-gon –20-gon –Decagon –Dodecagon

11. (n-2) x 180 video Cool Video!!

12. Theorem 2-4: Polygon Exterior Angle-Sum Theorem The sum of the measures of the exterior angles of a polygon, one at each vertex, is 360. http://www.mathlove.com/new3/product/img/TTA05/5.jpg

13. Video: General Definitions of Polygons

14. Definition Equilateral polygon: a polygon with all sides congruent. Equiangular polygon: a polygon with all angles congruent. Regular polygon: a polygon that is both equilateral and equiangular.

15. Homework Work Packet: Polygons