# Geometry Reference Libraries

Geometry is a branch of mathematics that is concerned with questions of shape, size, relative position of figures, and the properties of space. A mathematician who works in the geometry field is called a geometer. Geometry arose independently in numerous early cultures as a body of practical knowledge concerning areas, lengths, and volumes, with elements of a formal mathematical science...

Trigonometry, from the Greek trigonon, meaning triangle, and metron, meaning measure, is a branch of mathematics that studies the relationships involving lengths and angles of triangles. The field came about during the 3rd century BC from applications of geometry to astronomical studies. The 3rd century astronomers first noted that the lengths of the sides of a right triangle and the angles...

In geometry, a polygon is traditionally a plane figure that is bounded by a finite chain of strait line segments closing in a loop to create a closed chain or circuit. These line segments are called edges or sides, and the points where two of these edges meet are the polygon’s vertices or corners. The inside of the polygon is occasionally called its body. An n-gon is a polygon with n sides. A...

In Euclidean geometry, a rhombus, plural rhombi or rhombuses, is a simple quadrilateral whose four sides all have equal length. Another name is equilateral quadrilateral, since equilateral means that all of its sides are the same in length. The rhombus is frequently called a diamond, after the diamonds suit in the playing cards, or a lozenge, though the former sometimes is in reference...

Geometric and Functional Analysis (GAFA) is a bimonthly published mathematical journal published by Birkhauser, an independent division of Springer-Verlag. GAFA was founded in 1991 by Mikhail Gromov and Vitali Milman. The idea for the journal was inspired by the long-running Israeli seminar series “Geometric Aspects of Functional Analysis (GAFA)” of which Milman was one of the main...

Space -- The definition of space in physics is contentious. Various concepts used to try to define space have included: -- the structure defined by the set of "spatial relationships" between objects -- a manifold defined by a coordinate system where an object can be located. -- the entity that stops all objects in the universe from touching one another In classical physics,...

- In Roman antiquity, the return of a person who had been banished, or taken prisoner by an enemy, to his old condition and former privileges.
- In international law, that right by virtue of which persons and things taken by an enemy in war are restored to their former status when coming again under the power of the nation to which they belonged.