The base edges of a prism are the edges of the base of the prism.Ī vertex of a prism is a point of intersection of two base edges. The bases of a prism are the congruent polygons that lie in the parallel planes. Notice that the two polygons lie in parallel planes.Ī prism is the region formed by two parallel congruent polygons having corresponding vertices joined by line segments.

Two prisms (one based on a triangle, the other based on a rectangle) are shown in Figure 21.1. The result is a “solid” figure known as a prism. Let's draw line segments connecting each pair of corresponding vertices. After all, these are congruent polygons, and the corresponding vertices might want to maintain their connection.

They might just want to establish some sort of connection. That's not to say that they want to live in the same plane again. Now that your polygons have been separated, they might miss each other. It's a well-known fact that absence makes the heart grow fonder. The goal is to have the two polygons in parallel planes, with the same orientation. It doesn't have to be directly over (or under, if you chose to lower it) the other polygon you can move it sideways if the spirit moves you. Just lift it (or lower it, if you'd prefer) to a new plane that is parallel to the old plane. Don't twist it, or rotate it, or turn it in any way. Go ahead and move one of your polygons into a new plane. If your polygons don't get along, and the plane isn't big enough for the both of them, one of them will have to move.

Now you have two congruent polygons lying side by side. Suppose you have a polygon, like maybe a triangle or a rectangle, and you clone it. The Next Dimension: Surfaces and Solids.

Pentagonal prism