1. TODAY IN GEOMETRY…
Learning Goal: 1.6 Classify Polygons
Independent Practice – NO A.T.

2. POLYGON: a closed plane figure formed by three or more line segments.
sides
Polygons are named by listing vertices in consecutive order:
ABCDE
BCDEA
CDEAB
DEABC
EABCD A B E C
vertex D

3. CONVEX POLYGON: polygon with all interior angles less than 180°.
No lines that contain the sides goes through the interior of the polygon.

4. CONCAVE POLYGON: polygon with one or more interior angles greater than 180°.
One or more lines that contain the sides, goes through the interior of the polygon.
interior

5. 1. 2. Not a polygon Convex polygon 3. 4. Concave polygon Not a polygon
PRACTICE: Tell whether the figure is a polygon and whether it is concave and convex. 1. 2.
Not a polygon
Convex polygon 3. 4.
Concave polygon
Not a polygon

6. NAMING POLYGONS: polygons are named by the number of sides they have.
Type of Polygon 3 9 4 10 5 11 6 12 7 n 8
Triangle
Nonagon
Quadrilateral
Decagon
Pentagon
Hendecagon
Hexagon
Dodecagon
Heptagon
n-gon
Octagon
**Name any polygon larger than 12 sides with n-gon.
Example: 14 sided polygon is a 14-gon

7. EQUILATERAL POLYGON: polygon with all congruent sides.
Equilateral hexagon

8. EQUIANGULAR POLYGON: polygon with all congruent interior angles.
Equiangular hexagon

9. REGULAR POLYGON: a convex polygon that is both equilateral and equiangular.
Regular Pentagon

10. 1. 2. Regular hexagon Equilateral Equiangular Quadrilateral
PRACTICE: Classify the polygons by the number of sides. Tell whether the polygon is equilateral, equiangular, or regular. 1. 2.
Regular hexagon
Equilateral
Equiangular
Quadrilateral
Not equilateral
Not equiangular

11. PRACTICE: Find the length of one side of the regular hexagon.
Sides of a regular hexagon are congruent:
3𝑥+6=4𝑥−2
− 3𝑥 − 3𝑥
6=𝑥−2
𝟖=𝒙
Substitute x to find one length: 3𝑥+6
=3 8 +6
=𝟑𝟎
3𝑥+6
4𝑥−2

12. HOMEWORK #7:
Pg. 44: 3-13, 15-17, 24-30
If finished, work on other assignments:
HW #1: Pg. 5: 1, 5, 8-11, 13, 15, 17-21, 27-30, 46
HW #2: Pg. 12: 6-16, 21-28, 33, 35
HW #3: Pg. 19: 5-19, 25-27
HW #4: Pg. 20: 31-34, 43-45, 50-52
HW #5: Pg. 29: 7-27, 33-38, 45, 47, 50, 52, 62
HW #6: Pg. 38: 4-43 odd, 46-52