quadrant (redirected from quarter-circle)

quadrant, in analytic geometry

quadrant.

1 In analytic geometry, one of the four regions of the plane determined by two lines, the x-axis and the y-axis. Commonly these lines are drawn perpendicular to each other, and the quadrants, or regions, they determine are numbered counterclockwise, beginning with the upper right quadrant.

2 In geometry, a region of a plane determined by two perpendicular radii of a circle and the circle itself. Thus two perpendicular diameters of a circle divide it into four regions, or quadrants.

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quadrant, in technology

quadrant, in technology, angle-measuring device based on a scale of 90°. It is sometimes confused with the sextant, a similar instrument based on a scale of 60°. The quadrant is rarely used today.

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quadrant

1. Geometry

a. a quarter of the circumference of a circle

b. the area enclosed by two perpendicular radii of a circle and its circumference

c. any of the four sections into which a plane is divided by two coordinate axes

2. a piece of a mechanism in the form of a quarter circle, esp one used as a cam or a gear sector

3. an instrument formerly used in astronomy and navigation for measuring the altitudes of stars, consisting of a graduated arc of 90? and a sighting mechanism attached to a movable arm