## Tuesday, July 24, 2007

### Geometry Chapter 6.1 Polygons

6.1 Polygons

check out this website:

http://www.math.com/tables/geometry/polygons.htm

A) Polygon - is a plane figure with 3 or more sides, with each side intersecting with exactly 2 other sides, and that meets the following conditions:
1. If is formed by three or more segments called sides, such that no two sides with a common endpoint are collinear.
2. Each side intersects exactly two other sides, one at each endpoint.
3. each endpoint of a side is a vertex of the polygon.

B) Polygons are named by the numbe of sides they have.
3 sides = triangle
4 sides = quadrilateral
5 sides = pentagon
6 sides = hexagon
7 sides = heptagon
8 sides = octagon
9 sides = nonagon
10 sides = decagon
12 sides = dodecagon
n sides = n-gon
C) A polygon is convex if no line that contains a side of the polygon contains a point in the interior of the polygon.
D) a polygon that that is not convex is called nonconvex or concave.
E) Equilateral - a polygon with all of its side are congruent.
F) Regular - a polygon that is equilateral and equiangular.
G) Diagonal of a Polygon: A segment that joins 2 nonconsecutive vertices.
H) Theorem:
1) Interior Angles of a quadrilateral - the sum of the measures of the interior angles of a quadrilateral is 360 degrees.