MoM2

• A solid is a three-dimensional figure bounded by surfaces or plane figures.
• Solid figures are not limited to one plane and have depth.
• Polyhedron- is a solid bounded by planes
• Faces- are the portions of the bounding planes enclosed by the edges
• Edges- are the intersections of the bounding planes in a polyhedron
• Vertex/Vertices- are the intersections of the edges
• Section- of a solid is the plane figure cut from the solid by passing a plane through it.
• 5 A polyhedron is a three-dimensional figure that is formed by polygons that enclose a region in space
• NON-POLYHEDRONS - ders They have sides that are not pol
• A prism is a polyhedron with two parallel , congruent bases. The other faces, also called lateral faces, are rectangles.
• A pyramid is a polyhedron with one base and the lateral sides (all are triangular sides) meet at a common vertex
• Euler’s Theorem - Notice that faces + vertices is two more that the number of edges
• A regular polyhedron is a polyhedron where all the faces are congruent regular polygons
• Regular Tetrahedron: A 4-faced polyhedron and all the faces are equilateral triangles.
• Cube: A 6-faced polyhedron and all the faces are squares.
• Regular Octahedron: An 8-faced polyhedron and all the faces are equilateral triangles
• Regular Dodecahedron: A 12-faced polyhedron and all the faces are regular pentagons
• Regular Icosahedron: A 20-faced polyhedron and all the faces are equilateral triangles
• One way to “view” a three-dimensional figure in a two-dimensional plane is to use cross-sections.
• A cross-section is the intersection of a plane with a solid
• A net is an unfolded, flat representation of the sides of a three-dimensional shape.