geometry

/dʒiˈɑmətri/

/dʒiˈɒmətri/

Other forms: geometries

Geometry is the part of mathematics that deals with calculating the distance around a circle, the angles that make up a triangle, or the amount of room inside a cube. If it involves measuring space, it’s probably geometry.

The Greek roots of geometry literally mean “to measure earth,” and over 5000 years ago farmers started using geometry to figure out how much land they owned. You study geometry in school, and you use it all the time, like calculating the best angle to cut a piece of wood for a birdhouse, or when playing a game of pool. Astronomers use geometry to measure planets millions of miles away—much easier than finding a ruler that big.

Definitions of geometry

1. noun

   the pure mathematics of points and lines and curves and surfaces
   types:

   affine geometry

   the geometry of affine transformations

   Euclidean geometry, elementary geometry, parabolic geometry

   (mathematics) geometry based on Euclid's axioms

   fractal geometry

   (mathematics) the geometry of fractals

   non-Euclidean geometry

   (mathematics) geometry based on axioms different from Euclid's

   spherical geometry

   (mathematics) the geometry of figures on the surface of a sphere

   analytic geometry, analytical geometry, coordinate geometry

   the use of algebra to study geometric properties; operates on symbols defined in a coordinate system

   plane geometry

   the geometry of 2-dimensional figures

   solid geometry

   the geometry of 3-dimensional spaces

   descriptive geometry, projective geometry

   the geometry of properties that remain invariant under projection

   hyperbolic geometry

   (mathematics) a non-Euclidean geometry in which the parallel axiom is replaced by the assumption that through any point in a plane there are two or more lines that do not intersect a given line in the plane

   Riemannian geometry, elliptic geometry

   (mathematics) a non-Euclidean geometry that regards space as like a sphere and a line as like a great circle

   type of:

   pure mathematics

   the branches of mathematics that study and develop the principles of mathematics for their own sake rather than for their immediate usefulness