A plane that intersects all edges of a prism determines in it a region called the prism section.

Cross section is a region determined by the intersection of the prism with a plane parallel to the base planes (figure 1). All cross sections are congruent (Figure 2).

## Areas

In a prism, we distinguish two types of surface: the faces and the bases. So we have to consider the following areas:

a) area of a face (**THE**_{F} ): area of one of the parallelograms that make up the faces;

b) lateral area (**THE _{L}**): sum of the areas of the parallelograms that form the faces of the prism.

In the regular light, we have:

THE_{L }= n. THE_{F} (n = number of sides of base polygon)

c) base area (**THE _{B}**): area of one of the base polygons;

d) total area (**THE _{T}**): sum of the lateral area with the base area.

THE_{T} = A_{L} + 2A_{B}

Let's look at an example. Given a regular hexagonal prism of base edge **The** and side edge **H**we have:

_{}