1-7 Three-Dimensional Figures

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1-7 Three-Dimensional Figures

• What is a polyhedron?
• How are polyhedrons classified?
• What are Platonic solids?

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You identified and named two-dimensional figures.

• Identify and name three-dimensional figures.

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Definitions

• A polyhedron is a solid with all flat surfaces
  that enclose a single region of space.
• A face is each flat surface of the polygon
• Faces are named in the same way as polygons.
• Edges are the line segments where the faces
  intersect.
• A vertex is the point where three or more edges
  meet.
• Polyhedrons or polyhedra are named by the shape
  of their bases and type of solid.

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• Prisms and pyramids are Polyhedrons.
• Cylinders, cones and spheres are not.

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Bases

• The bases of the figure are the two parallel
  congruent faces of the three dimensional figure.
• BEWARE!!
• The figure may not be sitting on its base

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Naming polyhedrons

• Polyhedrons are named by the shape of their bases.

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Identify Solids
Determine whether the solid is a polyhedron. Then
identify the solid. If it is a polyhedron, name
the bases, faces, edges, and vertices.
The solid is formed by polygonal faces, so it is
a polyhedron. The bases are rectangles. This
solid is a rectangular prism.
Answer rectangular prism
Bases rectangles EFHG, ABDC Faces rectangles
FBDH, EACG, GCDH,EFBA, EFHG,
ABDC Vertices A, B, C, D, E, F, G, H
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Identify Solids
Determine whether the solid is a polyhedron. Then
identify the solid. If it is a polyhedron, name
the bases, faces, edges, and vertices.
The solid has a curved surface, so it is not a
polyhedron. The base is a circle and there is one
vertex. So, it is a cone.
Answer Base circle TVertex Wno faces or
edges
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Identify the solid
A. triangular prism B. triangular
pyramid C. rectangular pyramid D. cone
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Platonic Solids
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Identify the solid
A. cone B. cylinder C. pyramid D. polyhedron
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Identify the solid
A. triangular pyramid B. pentagonal
prism C. rectangular prism D. square pyramid
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• What is a polyhedron?
• A polyhedron is a solid whose faces are polygons.
• How are polyhedrons classified?
• Polyhedrons are named by the shape of their
  bases.

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Assignment 1-7

• Page 70, 1, 2, 6-16, skip 12