DEFINING POLYGONS

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DEFINING POLYGONS

• 2.5

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Polygon A polygon is a closed geometric figure
in a plane, formed by connecting line segments
endpoint to endpoint with each segment
intersecting exactly two others.
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SideA line segment of a polygon
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VertexAn endpoint where the sides of a polygon
meet
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Convex PolygonA polygon where no segment
connecting two vertices is outside the polygon
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Concave PolygonA polygon in which at least one
segment connecting two vertices is outside the
polygon
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Classifying Polygons
Polygons are classified according to the number
of sides they have (see page 99)
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ConsecutiveWhere numbers, letters or figures are
next to or touching each other
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Labeling (Naming) Polygons--
Polygons are labeled (named) by listing the
capital letters of the vertices in consecutive
order
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D
C
E
B
F
A
Hexagon ABCDEF
Hexagon FEDCBA
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For the triangle only we have a symbol so we
don't have to write "triangle"
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Consecutive VerticesTwo vertices of a polygon
connected by a side
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Consecutive SidesTwo sides which share a common
vertex
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Consecutive AnglesTwo angles which share a
common side
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Congruent PolygonsTwo or more polygons are
congruent iff they have the same size and shape.
The corresponding angles and sides are congruent.
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P
M
T
E
C
A
S
I
Trap CAMP Trap SITE
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• Perimeter ? The sum of the lengths of the sides
  of a polygon.

Perimeter 12181218 60 m
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• Diagonal of a Polygon ? A segment is a diagonal
  of a polygon if-and-only-if it connects any two
  nonconsecutive vertices.

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• Equilateral Polygon ? A polygon is an
  equilateral polygon if-and-only-if all of the
  sides are equal in measure.

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• Equiangular Polygon ? A polygon is an equiangular
  polygon if-and-only-if all of the angles are
  equal in measure.

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• Regular Polygon ? A polygon is an equilateral
  polygon if-and-only-if it is BOTH equilateral and
  equiangular.