6-1 properties and attributes of polygons
TRANSCRIPT
Holt McDougal Geometry
6-1 Properties and Attributes of Polygons
Bellringer:
1. A ? is a three-sided polygon.
2. A ? is a four-sided polygon.
Evaluate each expression for n = 6.
3. (n – 4) 12
4. (n – 3) 90
Solve for a.
5. 12a + 4a + 9a = 100
triangle
quadrilateral
24
270
4
Holt McDougal Geometry
6-1 Properties and Attributes of Polygons
Classify polygons based on their sides and angles.
Find and use the measures of interior and exterior angles of polygons.
Objectives
Holt McDougal Geometry
6-1 Properties and Attributes of Polygons
side of a polygon
vertex of a polygon
diagonal
regular polygon
concave
convex
Vocabulary
Holt McDougal Geometry
6-1 Properties and Attributes of Polygons
In Lesson 2-4, you learned the definition of a polygon. Now you will learn about the parts of a polygon and about ways to classify polygons.
Holt McDougal Geometry
6-1 Properties and Attributes of Polygons
A polygon is a closed plane figure formed by three or more segments that intersect only at their endpoints.
Remember!
Holt McDougal Geometry
6-1 Properties and Attributes of Polygons
Each segment that forms a polygon is a side of the polygon. The common endpoint of two sides is a vertex of the polygon. A segment that connects any two nonconsecutive vertices is a diagonal.
Holt McDougal Geometry
6-1 Properties and Attributes of Polygons
You can name a polygon by the number of its sides. The table shows the names of some common polygons.
Holt McDougal Geometry
6-1 Properties and Attributes of Polygons
Example 1A: Identifying Polygons
Tell whether the figure is a polygon. If it is a polygon, name it by the number of sides.
hexagon
Holt McDougal Geometry
6-1 Properties and Attributes of Polygons
Example 1B: Identifying Polygons
Tell whether the figure is a polygon. If it is a polygon, name it by the number of sides.
Holt McDougal Geometry
6-1 Properties and Attributes of Polygons
Example 1C: Identifying Polygons
Tell whether the figure is a polygon. If it is a polygon, name it by the number of sides.
Holt McDougal Geometry
6-1 Properties and Attributes of Polygons
Check It Out! Example 1a
Tell whether each figure is a polygon. If it is a polygon, name it by the number of its sides.
Holt McDougal Geometry
6-1 Properties and Attributes of Polygons
Check It Out! Example 1b
Tell whether the figure is a polygon. If it is a polygon, name it by the number of its sides.
Holt McDougal Geometry
6-1 Properties and Attributes of Polygons
All the sides are congruent in an equilateral polygon. All the angles are congruent in an equiangular polygon. A regular polygon is one that is both equilateral and equiangular. If a polygon is not regular, it is called irregular.
Holt McDougal Geometry
6-1 Properties and Attributes of Polygons
A polygon is concave if any part of a diagonal contains points in the exterior of the polygon. If no diagonal contains points in the exterior, then the polygon is convex. A regular polygon is always convex.
Holt McDougal Geometry
6-1 Properties and Attributes of Polygons
Example 2A: Classifying Polygons
Tell whether the polygon is regular or irregular. Tell whether it is concave or convex.
Holt McDougal Geometry
6-1 Properties and Attributes of Polygons
Example 2B: Classifying Polygons
Tell whether the polygon is regular or irregular. Tell whether it is concave or convex.
irregular
concave
Holt McDougal Geometry
6-1 Properties and Attributes of Polygons
Example 2C: Classifying Polygons
Tell whether the polygon is regular or irregular. Tell whether it is concave or convex.
regular
convex
Holt McDougal Geometry
6-1 Properties and Attributes of Polygons
Check It Out! Example 2a
Tell whether the polygon is regular or irregular. Tell whether it is concave or convex.
regular
convex
Holt McDougal Geometry
6-1 Properties and Attributes of Polygons
Check It Out! Example 2b
Tell whether the polygon is regular or irregular. Tell whether it is concave or convex.
irregular
concave