What are the plat surfaces on a pyramid cube or rectangular prism called?

Answer 1

faces

Answer 2

The flat surfaces on a pyramid are called faces. A pyramid has one base and triangular faces that meet at a single point called the apex. On a cube or rectangular prism, the flat surfaces are called faces as well. But unlike a pyramid, a cube has six square faces, while a rectangular prism has two rectangular bases and four rectangular faces.