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Number your paper. 1. 2. 3. 4. 5. 6. Classifying polygons by number of sides. 1. 2. 3. 4. 5. 6. See text!. A regular polygon is one that is both equilateral and equiangular. If a polygon is not regular, it is called irregular.
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Number your paper 1. 2. 3. 4. 5. 6.
Classifying polygons by number of sides. 1 2 3 4 5 6 See text!
A regular polygonis one that is both equilateral and equiangular. If a polygon is not regular, it is called irregular. Concave: any diagonal passes outside of the polygon Convex:no diagonal passes outside the polygon regular irregular
Number your paper 1. 2. 3. 4. 5.
Tell whether each polygon is regular or irregular and concave or convex. 1 2 5 4 3
Draw these! 1. 2. 3. 4. 5.
Examples: Sketch a polygon that meets each of the following characteristics, if possible. Sketch! • convex, irregular hexagon • concave triangle. • Regular quadrilateral • convex nonagon • concave, regular pentagon
Find the sum of the interior angle measures of each convex polygon by drawing all possible diagonals from one vertex of the polygon. How does the triangle sum theorem help you?
Work it! Example 1: Find the sum of the interior angle measures of a convex heptagon.
Work it! Example 2: Find the measure of each interior angle of pentagon ABCDE.
Talk about it! How would you calculate the measure of each interior angle of a regular decagon? What if it’s not regular?
Talk about it! What is the measure of each interior angle of a regular decagon? What is the measure of each exterior angle of a regular decagon? What is the SUM of allof the exterior angles?
Watch it! In the polygons below, an exterior angle has been measured at each vertex. Notice that in each case, the sum of the exterior angle measures is 360°.
Work it! Example 3: Find the value of b in polygon FGHJKL.
Work it! Example 4 Find the measure of each exterior angle of a regular 20-gon.
Talk about it! Ann is making paper stars for party decorations. If the pentagon in the center of the star is regular, what is the measure of 1? 2? 2