Introduction
Geometry is the study of how to use math to describe and investigate different points, lines, and shapes. The way that a shape is described in geometry is with a mathematical calculation called a formula. Formulas can be used to describe the relationships among different parts of a shape, including its length, width, and height.
A rectangle drawn on a piece of paper is a two-dimensional shape. This means it has two dimensions: height and length. But real-world objects are three-dimensional shapes (sometimes called solids). They have three dimensions: height, length, and width. A rectangular box, like a juice box or cereal box, is called a rectangular prism in geometry.