1. 7-5 Polygons Course 2 Warm Up Warm Up Problem of the Day Problem of the Day Lesson Presentation Lesson Presentation

2. Course 2 7-5 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 7-5 Polygons

4. Learn to identify and name polygons. Course 2 7-5 Polygons

5. Vocabulary polygon side vertex of a polygon regular polygon Insert Lesson Title Here Course 2 7-5 Polygons

6. Course 2 7-5 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. The polygon at left has six sides and six vertices. Vertices is plural for vertex. Remember! Side Vertex

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

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

9. Determine whether each figure is a polygon. If it is not, explain why not. Try This: Example 1A & 1B Course 2 7-5 Polygons 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. Determine whether each figure is a polygon. If it is not, explain why not. Try This: Example 1C & 1D Course 2 7-5 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 cross.

11. Course 2 Polygons 7-5 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. Name each polygon. Additional Example 2: Classifying Polygons Course 2 7-5 Polygons A. Octagon B. Quadrilateral

13. Try This: Example 2 Name each polygon. Insert Lesson Title Here Course 2 7-5 Polygons A. B. Quadrilateral Pentagon

14. Insert Lesson Title Here Course 2 7-5 Polygons 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 7-5 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.

16. Try This: Example 3 Insert Lesson Title Here Course 2 7-5 Polygons 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.

17. Lesson Quiz Determine whether each statement is true or false. 1. Every polygon is a closed figure. 2. Every open figure is a polygon. 3. A pentagon with sides lengths of 10 units and angles measuring 108° is a regular polygon. 4. A quadrilateral with side lengths of 10, 12, 10, and 12 units is a regular polygon. 5. What is the name of a five-sided polygon? false true Insert Lesson Title Here true false Course 2 7-5 Polygons pentagon