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

2. 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. 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: Course 2 8-5 Classifying Polygons

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

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

6. 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. Triangles and rectangles are examples of polygons. The polygon at left has six sides and six vertices. Vertices is plural for vertex. Remember! Side Vertex Course 2 8-5 Classifying Polygons

7. Determine whether each figure is a polygon. If it is not, explain why not. Additional Example 1: Identifying Polygons 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. Course 2 8-5 Classifying Polygons

8. Determine whether each figure is a polygon. If it is not, explain why not. Additional Example 1: Identifying Polygons 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. Course 2 8-5 Classifying Polygons

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

10. Determine whether each figure is a polygon. If it is not, explain why not. Check It Out: Example 1 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. Course 2 8-5 Classifying Polygons

11. 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 Course 2 8-5 Classifying Polygons

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

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

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

15. 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. The figure is a regular quadrilateral. A regular quadrilateral is also called a square. The figure is a quadrilateral. It is not a regular polygon because all of the sides are not congruent. A. B. Course 2 8-5 Classifying Polygons

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

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

18. 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. Insert Lesson Title Here no; curved lines 1: No, all sides and angles are not congruent. 2, 4: No, they are not polygons. 3: Yes Course 2 8-5 Classifying Polygons