Geometry Geometry is the part of maths that is about the properties of shapes like triangles, squares, circles, cubes, and spheres. It is about measuring distances and angles between lines and working out rules for two dimensional and three dimensional things. Its opposite is arithmetic, which is about numbers and equations and doing calculations such as multiplication and division. Geometry is one of the oldest parts of maths. The word geometry comes from the Greek word meaning 'Earth measurement'. One of the first people to write about Geometry was Euclid, in his Elements of Geometry, which was written in about 300 BC. In the Middle Ages geometry was taught in universities as one of the four mathematical subjects called the 'quadrivium', along with arithmetic, astronomy and music (which was taught in a very mathematical way). Geometry is very important to many practical jobs such as architecture, surveying and navigating. It is also used in painting: painters use a special kind of geometry called linear perspective to make sure that their paintings look real.