1. Holt CA Course 1 9-5 Classifying Polygons Preparation for MG2.3 Draw quadrilaterals and triangles from given information about them (e.g., a quadrilateral having equal sides but no right angles, a right isosceles triangle). California Standards

2. Holt CA Course 1 9-5 Classifying Polygons Vocabulary polygon vertex regular polygon

3. Holt CA Course 1 9-5 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. Each side meets exactly two other sides, one on each end, in a common endpoint. Each endpoint is a vertex of the polygon. The polygon at left has six sides and six vertices. Vertices is plural for vertex. Remember! Side Vertex

4. Holt CA Course 1 9-5 Classifying Polygons Determine whether each figure is a polygon. Explain your answer. 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.

5. Holt CA Course 1 9-5 Classifying Polygons Determine whether each figure is a polygon. Explain your answer. 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 sides that meet more than 2 other sides.

6. Holt CA Course 1 9-5 Classifying Polygons Determine whether each figure is a polygon. Explain your answer. 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.

7. Holt CA Course 1 9-5 Classifying Polygons Determine whether each figure is a polygon. Explain your answer. 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 sides that meet more than two other sides.

8. Holt CA Course 1 9-5 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

9. Holt CA Course 1 9-5 Classifying Polygons Name each polygon. Additional Example 2: Classifying Polygons A. Octagon B. Quadrilateral 8 sides, 8 angles 4 sides, 4 angles

10. Holt CA Course 1 9-5 Classifying Polygons Check It Out! Example 2 Name each polygon. A. B. Quadrilateral Pentagon 4 sides, 4 angles 5 sides, 5 angles

11. Holt CA Course 1 9-5 Classifying Polygons A regular polygon is a polygon in which all sides are congruent and all angles are congruent.

12. Holt CA Course 1 9-5 Classifying Polygons Additional Example 3: Identifying and Classifying Regular Polygons Name each polygon and tell whether it is a regular polygon. Explain your answer. The figure has congruent angles and congruent sides. It is a regular quadrilateral. The figure is a quadrilateral. It is not a regular polygon because all of the sides are not congruent. A. B.

13. Holt CA Course 1 9-5 Classifying Polygons A polygon with congruent sides is not necessarily a regular polygon. Its angles must also be congruent. Caution!

14. Holt CA Course 1 9-5 Classifying Polygons Check It Out! Example 3 The figure is a triangle. It is not a regular polygon because all sides and angles are not congruent. The figure has congruent angles and congruent sides. It is a regular triangle. Name each polygon and tell whether it is a regular polygon. If it is not, explain why not. A. B.