Polyhedrons 10-5
A polyhedron is a figure formed of polygonal parts of planes that enclose a region of space.
A prism is a polyhedron that has two congruent regions called bases that are parallel. Prisms are named according to their bases. Thus, a box is a rectangular prism. Take a look at Page 339 for some more examples of prisms.
A pyramid has only one base and a vertex. It is also named by the shape of its base. A triangular pyramid is also called a tetrahedron.
A regular polyhedron has all of its faces bounded by congruent regular polygons. There are only five such polyhedrons having 4, 6, 8, 12, and 20 faces.
Regular tetrahedron, cube, regular octahedron, regular dodecahedron, and regular icosahedron.
Check out Page 340 in our textbook for a picture of these.
Volumes Of Prisms 10-6
A polyhedron together with the region inside it is called a solid. The measure of the space occupied by a solid is called the colume ofthe solid.
Volume of prism = Base area X height
V = Bh where B = the Base area or the area of the base
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