quadrant

n.

1. Mathematics.
   1. A circular arc of 90°; one fourth of the circumference of a circle.
   2. The plane area bounded by such an arc and two perpendicular radii.
   3. Any of the four areas into which a plane is divided by the reference axes in a Cartesian coordinate system, designated first, second, third, and fourth, counting counterclockwise from the area in which both coordinates are positive.
2. A machine part or other mechanical device that is shaped like a quarter circle.
3. An early instrument for measuring altitude of celestial bodies, consisting of a 90° graduated arc with a movable radius for measuring angles.

[Middle English, quarter of a day, from Latin quadrāns, quadrant-, a fourth part.]

n

One quarter of a circle; also used to describe one fourth of the combined dental arches. One half of the maxillary dental arch is one quadrant of the combined dental arches.

[ܒkwädrǝnt]

ˈkwädrǝnt n. 1. an instrument used for taking angular measurements of altitude in astronomy and navigation, typically consisting of a graduated quarter circle and a sighting mechanism.

2. a frame fixed to the head of a ship's rudder, to which the steering mechanism is attached.

See the Introduction, Abbreviations and Pronunciation for further details.

[Etymology: a quarter of a revolution] length A quarter of Earth's circumference, particularly from Equator along a meridian, nominally 10 000 000 m, by the original definition of the metre (6 213.7~ mi), but actually slightly greater, which is more of a problem to coordinate systems than were it less.

plane angle The right angle, = 90° (1.570 796~ rad).

electrics The original name of the henry.

1. An angle-measuring instrument used for measuring elevations.
2. A quarter-round molding.
3. A device for fastening together the upper and lower leaves of a Dutch door.
4. A quadrant stay.

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1. one-quarter of the circumference of a circle.
2. one of four corresponding parts, or quarters, as of the surface of the abdomen or of the field of vision.

To convert from quadrants (angle) to:

degrees, multiply by 90.
minutes, multiply by 5400.
radians, multiply by 1.571.
seconds, multiply by 3.24E+05.

Convert:  Into:  degrees minutes radians seconds

Result:

Measuring the angular height of a heavenly body at sea
A quadrant is one of the simplest instruments ever devised for celestial navigation and was well known to the early Arab seafarers. In its crudest form, it’s just a 90-degree protractor with a plumb bob hanging from its apex. Its name refers to the fact that it measures one fourth of a circle.Some of the first quadrants were large, measuring about 4 feet along the sighting arm, and it needed two people to take the altitude of a heavenly body—one to hold and aim the instrument, with the aid of two peepholes, and the other to take the angular reading from the arc.

Measuring the angular height, or declination, of the sun or a star with a quadrant.

At best, the quadrant could fix latitude within a degree, or 60 nautical miles, but in bad weather on a heaving deck it was all but impossible to use. According to Dennis Fisher, author of Latitude Hooks and Azimuth Rings, Christopher Columbus had a quadrant, but complained in his log about not being able to use it except in a flat calm—and even then it was off by as much as 19 degrees.Tycho Brahe, the sixteenth-century Danish astronomer, had a quadrant the size of a room to make his chart of the heavens, which Johannes Kepler subsequently used to make his great discoveries.The quadrant was gradually superseded by the cross-staff and the remarkably efficient backstaff, which was invented by the Englishman John Davis in about 1590 and remained in use, little changed, for more than 200 years. The first double-reflecting octant—the forerunner of the mirrored sextant—appeared around 1730.See also Backstaff; Sextant.

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IN BRIEF: One fourth of a circle. Also: An instrument used for measuring angles and heights.

One quadrant of the circle graph represents the people who are vegetarians.

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Dansk (Danish)
n. - kvadrant

Nederlands (Dutch)
kwadrant, graadboog, iets in de vorm van een kwartcirkel

Français (French)
n. - quadrant

Deutsch (German)
n. - Quadrant

Ελληνική (Greek)
n. - τεταρτημόριο, (αστρον., ναυτ.) τετράς (όργανο)

Italiano (Italian)
quadrante

Português (Portuguese)
n. - quadrante (m), quarta parte da circunferência, setor (m)

Русский (Russian)
квадрант, сектор

Español (Spanish)
n. - cuadrante

Svenska (Swedish)
n. - kvadrant

中文（简体）(Chinese (Simplified))
四分圆, 四分仪, 象限

中文（繁體）(Chinese (Traditional))
n. - 四分圓, 四分儀, 象限

한국어 (Korean)
n. - 사분원, 사분면, 상한

日本語 (Japanese)
n. - 4分円, 象限, 4分儀, 象限儀

العربيه (Arabic)
‏(الاسم) ربع دائرة, الربعيه مقياس, الارتفاع, القوس, في الهندسه‏

עברית (Hebrew)
n. - ‮רביע, רבע מעגל, מד-זווית, קוודרנט, חלק ממישור המחולק ע"י שני קווים מצטלבים בזווית ישרה‬

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