1. 8-5 Classifying Polygons Warm Up Problem of the Day
Course 2
Warm Up
Problem of the Day
Lesson Presentation

2. 8-5 Classifying Polygons Warm Up 1. How do you name a ray?
Course 2
8-5
Classifying Polygons
Warm Up
1. How do you name a ray?
Under the ray
symbol, name first the endpoint and then
any other point on the ray.
2. What is the measure of an obtuse angle?
between 90° and 180°
3. How do you name a line?
Under the line symbol, name any two
points on a line.
4. What is true of supplementary angles?
The sum of their measures is 180°.

3. 8-5 Classifying Polygons Problem of the Day
Course 2
8-5
Classifying Polygons
Problem of the Day
Draw a polygon with 10 congruent sides. Make 5 of the angles acute angles and the other 5 reflex angles (greater than 180°).
Possible answer:

4. Course 2
8-5
Classifying Polygons
Learn to identify and name polygons.

5. Insert Lesson Title Here
Course 2
8-5
Classifying Polygons
Insert Lesson Title Here
Vocabulary
polygon
regular polygon

6. 8-5 Classifying Polygons
Course 2
8-5
Classifying Polygons
Triangles and rectangles are examples of polygons. A polygon is a closed plane figure formed by three or more line segments. Each line segment forms a side of the polygon, and meets, but does not cross, another line
segment at a common point. This common point is a vertex of a polygon.
Side
Vertex
The polygon at
left has six
sides and six
vertices.
Vertices is plural for vertex.
Remember!

7. Additional Example 1: Identifying Polygons
Course 2
8-5
Classifying Polygons
Additional Example 1: Identifying Polygons
Determine whether each figure is a polygon. If it is not, explain why not. A. B.
The figure is a polygon. It is a closed figure with 4 line segments.
The figure is not a polygon. It is not a closed figure.

8. Additional Example 1: Identifying Polygons
Course 2
8-5
Classifying Polygons
Additional Example 1: Identifying Polygons
Determine whether each figure is a polygon. If it is not, explain why not. C. D.
The figure is not a polygon. The figure is not formed by line segments.
The figure is not a polygon. There are line segments in the figure that intersect.

9. 8-5 Classifying Polygons Check It Out: Example 1
Course 2
8-5
Classifying Polygons
Check It Out: Example 1
Determine whether each figure is a polygon. If it is not, explain why not. A. B.
The figure is a polygon. It is a closed figure with 5 line segments.
The figure is not a polygon. It is not a closed figure.

10. 8-5 Classifying Polygons Check It Out: Example 1
Course 2
8-5
Classifying Polygons
Check It Out: Example 1
Determine whether each figure is a polygon. If it is not, explain why not. C. D.
The figure is not a polygon. The figure is not formed by line segments.
The figure is not a polygon. There are line segments in the figure that intersect.

11. 8-5 Classifying Polygons
Course 2
8-5
Classifying Polygons
Polygons are classified by the number of sides
and angles they have.
Triangle
3 sides
3 angles
Quadrilateral
4 sides
4 angles
Pentagon
5 sides
5 angles
Hexagon
6 sides
6 angles
Heptagon
7 sides
7 angles
Octagon
8 sides
8 angles
Nonagon
9 sides
9 angles
Decagon
10 sides
10 angles

12. Additional Example 2: Classifying Polygons
Course 2
8-5
Classifying Polygons
Additional Example 2: Classifying Polygons
Name each polygon. A. B.
Octagon
Quadrilateral

13. Insert Lesson Title Here
Course 2
8-5
Classifying Polygons
Insert Lesson Title Here
Check It Out: Example 2
Name each polygon. B. A.
Quadrilateral
Pentagon

14. Insert Lesson Title Here
Course 2
8-5
Classifying Polygons
Insert Lesson Title Here
A regular polygon is a polygon in which all sides are congruent and all angles are congruent.

15. Additional Example 3: Identifying and Classifying Regular Polygons
Course 2
8-5
Classifying Polygons
Additional Example 3: Identifying and Classifying Regular Polygons
Name each polygon and tell whether it is a
regular polygon. If it is not, explain why not. B. A.
The figure is a
quadrilateral. It is not a
regular polygon because
all of the sides are not
congruent.
The figure is a regular
quadrilateral. A regular quadrilateral is also called a square.

16. Insert Lesson Title Here
Course 2
8-5
Classifying Polygons
Insert Lesson Title Here
Check It Out: Example 3
Name each polygon and tell whether it is a
regular polygon. If it is not, explain why not. B. A.
The figure is a triangle. It is not a regular polygon because all sides and angles are not congruent.
The figure is a regular triangle.

17. Insert Lesson Title Here
Course 2
8-5
Classifying Polygons
Insert Lesson Title Here
Lesson Quiz: Part I
Determine whether each figure is a polygon. If it in not, explain why not. Name each polygon. 1. 2. 3.
yes; pentagon
no; open figure
yes; octagon

18. Insert Lesson Title Here
Course 2
8-5
Classifying Polygons
Insert Lesson Title Here
Lesson Quiz: Part II
Determine whether each figure is a polygon. If it in not, explain why not. Name each polygon. 4.
5. Tell whether each figure above is a regular t polygon. If it is not, explain why not.
no; curved lines
1: No, all sides and angles are not congruent.
2, 4: No, they are not polygons.
3: Yes