Note 4.2 Polygons and Polyhedra

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Note 4.2 Polygons and Polyhedra

• Our goals are to
• Identify and classify polygons
• Identify the faces, edges, and vertices of
  polyhedra

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Whats a polygon?

• Glad you asked!
• A polygon is a 2-dimensional closed figure (no
  open sides)
• The corners of the polygon are called the
  vertices.
• We classify polygons by the number of sides

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So, whats NOT a polygon?

• Any shape that is not completely connected or has
  gaps
• Any shape that has sides that intersect or cross
  each other
• Any shape that has curved edges
• Polygons must have straight sides.

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Why arent the following figures polygons?
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Regular and Not Regular

• Polygons are regular if all its sides are
  congruent and all its angles are congruent
• Polygons are NOT regular if their sides are of
  different lengths or if their angles are of
  different measures.

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Example 1Identify the polygon. Explain why it
is regular or not regular.
Now do the Massive Munchies and Cartoon Character
Worksheets.

• Which one of the following is a regular polygon?
  Explain. Also tell why the others are not.
• Circle B. Rhombus
• C. Rectangle D. Equilateral Triangle

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All about triangles.

• A triangle is a polygon with 3 sides.
• A triangle can be classified by its sides.
• The hash marks on the sides mean the sides are
  equal
• Arcs in the angles mean the angles are equal

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Example 2Classify each triangle according to its
sides and angles.
Now, do Singing Success and Heavy Hail Worksheets.
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Whats a polyhedron?

• A polyhedron is a 3-dimensional closed figure.
• The sides of the polyhedron are called faces
• The line segments of are called the edges.
• The corners are called the vertices

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Example 3Identify the number of faces, vertices,
and edges for the figure.
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Homework 4.2 Page 162-163 1-7 all, and 9-24 all,
and 37-39 all
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