Polygons

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Polygons
Section 2-2
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Polygon

• Closed plane figure with at least three sides
• The sides intersect only at their endpoints
• No adjacent sides are collinear
• To name a polygon
• Start at any vertex and list vertices
  consecutively.

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Names of Polygons
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Names of Polygons (cont)
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Theorem 2-3Polygon Interior Angle-Sum Theorem

• The sum of the measures of the interior angles of
  a polygon with n sides
• (n 2) 180

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Theorem 2-4Polygon Exterior Angle-Sum Theorem

• The sum of the measures of the exterior angles of
  a polygon, one at each vertex, is 360

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Regular Polygon

• A polygon with all sides congruent and all angles
  congruent.
• A polygon that is both equilateral and equiangular

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To find each interior angle measure of regular
polygon

• The measure of each interior angle of a polygon
  with n sides
• (n 2) 180
• n

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Examples