**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.