1. Essential Question: What happened to Chapter 9? Answer: We’ll get back to it

2. 10-1: Naming Polygons A polygon is named by the number of sides or angles. PrefixNumber of Sides Name of Polygon PrefixNumber of Sides Name of Polygon Tri-3TriangleHepta-7Heptagon Quadri-4QuadrilateralOcta-8Octagon Penta-5PentagonNona-9Nonagon Hexa-6HexagonDeca-10Decagon

3. 10-1: Naming Polygons When we studied quadrilaterals in Chapter 8, we learned some rules that can be applied to all polygons. P Q R S T U A vertex is the point of intersection between two sides A segment whose two endpoints are nonconsecutive vertices is called a diagonal Consecutive vertices are the two endpoints of any side Sides that share a vertex are called consecutive sides

4. 10-1: Naming Polygons An equilateral polygon has all sides congruent, and an equiangular polygon has all angles congruent. A regular polygon is both equilateral and equiangular. Equilateral, but not equiangular Equiangular, but not equilateral Regular, both equilateral and equiangular

5. 10-1: Naming Polygons Identify polygon LMNOPQRS by its sides Octagon Determine whether the polygon appears to be regular or not regular. If not regular, explain why. Not regular.  L ≠  M Name two nonconsecutive sides LM & NO L M N O P Q R S

6. You can use the property of regular polygons (all sides are the same length) to find the perimeter. P = (# of sides) x (length of each side) Example Find the perimeter of a regular octagon whose sides are 7.6 centimeters long P = (8)(7.6) = 60.8 cm Y OUR T URN Find the perimeter of a regular decagon whose sides are 12 feet long. 120 ft

7. A polygon can also be classified as convex or concave. If all the diagonals lie in the interior of a polygon, then the polygon is convex. If any point of a diagonal lies outside the figure, then the figure is concave. (“caved” in) Convex polygonConcave polygon

8. 10-1: Naming Polygons Assignment Worksheet 10-1