The length of a line segmentMathworldPlanetmath is the distance between its endpoints. Length may be measured in meters, yards, abstract units, etc. For example, in the following diagram


AB is one unit long, BC is two units long, CD is a fifth of a unit, DE is four fifths of a unit, AC is three units, etc.

The concept of length as defined above is a special case of a general concept called measure.

In two-dimensional space, length usually goes along the x axis while height goes along the y axis. The same holds in three-dimensional space.

For trianglesMathworldPlanetmath, pentagonsMathworldPlanetmath, and higher n-gons (http://planetmath.org/BasicPolygon), it is customary to refer to the length of any of its sides as the length of the . The length of a circle’s side is called its circumferenceMathworldPlanetmath.

In set theoryMathworldPlanetmath, length refers to the number of elements a set (or one-dimensional array) has. This is also known as cardinality. For example, {2,5,11,23,47} has length 5.

Title length
Canonical name Length
Date of creation 2013-03-22 16:31:45
Last modified on 2013-03-22 16:31:45
Owner PrimeFan (13766)
Last modified by PrimeFan (13766)
Numerical id 17
Author PrimeFan (13766)
Entry type Definition
Classification msc 51D20
Classification msc 51-00
Classification msc 51M25
Related topic Area2
Related topic Volume2
Related topic BasicPolygon
Defines length of a polygonMathworldPlanetmathPlanetmath
Defines length of a set