Today's Class (17/04/09) 9A

Today in class we got our quizzes back and we went over some of the questions. Most of the problems we had involved quadratic formula or the formula used to square a sum. We learned this formula last year and you should remember it.



Then we corrected the review we had for homework. After we stareted learning Chapter 10 which talks about polygons.

A Polygon is a closed figure with finite coplanar sides which :
1.- sides that have a common endpoint are non-collinear
2.- each side intersect two other sides but only at the endpoints

Concave and Convex Polygons:

A concave polygon is a polygon that is one of the sides had a continuation; in this case purple line, it would go through on of the other sides.

A convex polygons is just a polygon that the continuation of the sides wouldn't intersect other sides, just like a triangle of a square.

Regular Polygon:

Polygon with all sides and angles congruent (ex: square)

Classification of polygons:

# of sides Names

3 triangle

4 quadrilateral

5 pentagon

6 hexagon

7 heptagon

8 octagon

9 nonagon

10 decagon

12 dodecagon

From 11 on, we just called them by the number plus -gon.

A diagonal:

a segment that connects one vertex to a nonadjacent vertex.

We are gonna continue with the lesson on Wednesday next week. Dont forget Monday we have a test on chapter 9 (so study!!!) and we dont have school on Tuesday!!!!