# Scientists Say: Geometry

## Geometry is the branch of math that deals with shapes and their properties

**Geometry **(noun, “Gee-AH-muh-tree”)

Geometry is the branch of math that deals with the size, shape and position of figures in space. This math dates back thousands of years to Egypt and Mesopotamia. At that time, people used these concepts to survey land, construct buildings and measure storage containers. The word “geometry” comes from the Greek words for “Earth” and “measure.” That’s fitting, since geometry deals with the properties and relationships of shapes around us. Today, architects and engineers use geometry to build houses and bridges. Astronomers use it to calculate the positions of stars. Even artists and video game designers use geometry in their work.

The most basic element in geometry is a unique spot in space called a point. A connected set of points forms a line. Intersecting lines form angles. Three or more joined line segments create shapes called polygons, such as triangles and squares. These and other flat shapes have only two dimensions: length and width. Three-dimensional objects — such as cubes and spheres — have the added dimension of depth.

Geometry allows people to measure, analyze and compare figures in 2-D and 3-D space. One useful tool for reaching conclusions about figures in geometry is a mathematical proof. A proof is a way of showing that some mathematical statement is true. It starts from known truths called axioms or postulates. For instance, all right angles are 90 degrees. And a straight line can be drawn between any two points. These truths are self-evident. They don’t have to be proved. But it’s possible to create a series of logical arguments using those facts to prove a new truth. Theorems are statements that can be proved. Perhaps the most famous is the Pythagorean theorem. This theorem states how to find the length of the longest side of a triangle that contains a right angle.

#### In a sentence

Some scientists use geometry to help athletes boost their performance.