The base is counted as a face. The base of a prism, cylinder, pyramid, and so on, is the flat surface shape that defines the outline of the object. In the case of a prism, the faces are always parallelograms; in the case of a pyramid, the faces are always triangles. For either of those solids, the shape of the base can be any convex polygon. For rectangular prisms, and for triangular pyramids, any face could be a base.
When figuring the volume of the object, the base area and the height measured from the base constitute the measurements of interest. (One also needs to know whether the object tapers to a point, or has a uniform cross-sectional area.)
When figuring the volume of the object, the base area and the height measured from the base constitute the measurements of interest. (One also needs to know whether the object tapers to a point, or has a uniform cross-sectional area.)
