# Distance

(redirected from*source-to-image receptor distance*)

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## distance

**1.**

*Geometry*

**a.**the length of the shortest line segment joining two points

**b.**the length along a straight line or curve

**2.**

*Horse racing*

**a.**

*Brit*a point on a racecourse 240 yards from the winning post

**b.**

*Brit*any interval of more than 20 lengths between any two finishers in a race

**c.**

*US*the part of a racecourse that a horse must reach in any heat before the winner passes the finishing line in order to qualify for later heats

**3.**

**go the distance**

*Boxing*to complete a bout without being knocked out

**4.**the distant parts of a picture, such as a landscape

**5.**

**middle distance**

**a.**(in a picture) halfway between the foreground and the horizon

**b.**(in a natural situation) halfway between the observer and the horizon

**6.**

*Athletics*relating to or denoting the longer races, usually those longer than a mile

*The Great Soviet Encyclopedia*(1979). It might be outdated or ideologically biased.

## Distance

distance in depth between servicemen, guns, vehicles, and subunits or units (ships) when formed in ranks, on the march (cruise), or in combat formation and also between aircraft when flying in formation or in a combat formation.

## Distance

an important geometric concept whose meaning depends on the kind of entities for which it is defined. The distance between two points is the length of the line segment joining the points. The distance from a point to a line or a plane is the length of the perpendicular from this point to the line or plane. The distance between two parallel lines or planes is the length of a common perpendicular to the lines or planes. The distance between two nonintersecting nonparallel lines in space is equal to the distance between the parallel planes in which the lines lie—that is, the length of the line segment that joins the lines and is perpendicular to both.