1. Sec 1-6
Concept: Polygons
Objective: Given a figure, we will identify and name it if it is a polygon as measured by a scoring guide

2. Vocabulary: Polygon: a plane figure that meets these 2 criteria
1. It is formed by three or more line segments called sides
2. each side intersects exactly two sides, one at each endpoint, so that no two sides with a common endpoint are collinear. S N O W
Vertex
Polygon SNOW

3. Example 1: Determine which shapes are polygons
Example 1: Determine which shapes are polygons. If a shape is a polygon, then state if it is concave or convex. A B C D
concave
convex
A - yes
B - no
C - yes
D - yes

4. Names of Polygons: Handout
You have 10 min. to do this handout, then we will go over it

5. Regular Polygon:
A regular polygon is both equilateral and equiangular

6. Example 2: Each figure is a regular polygon
Example 2: Each figure is a regular polygon. Expressions are given for two sides lengths. Find the value of x.
x2+5x+13
x2+10x-7
7x+34
11x-14
x2+5x+13 = x2+10x-7
20=5x
4=x
7x+34 = 11x-14
48=4x
12=x

7. Example 3: The expressions (3x+63)° and (7x-45)° represent the measures of two angles of a regular decagon. Find the measure of an angle of the decagon.
3x+63=7x-45
108=4x
27=x
3(27)+63
=144°

8. Example 4: Draw a figure that fits the description.
A quadrilateral that is not regular
A concave pentagon

9. Example 5 # 31 p. 46

10. Example 6 # 33 & 36 p. 46

11. Today’s Work: