The x- and y-axes the xy-plane in four right-angle domains which are called the quadrantsMathworldPlanetmath of the plane.  They are numbered going round the origin in anticlockwise direction so that


is the first quadrant,


the second quadrant, and so on.

Naturally, one can speak of the quadrants of the complex planeMathworldPlanetmath, too.

The lines y=±x have as their slope angles ±45, thus halving the quadrant angles; they are called the quadrant bisectorsMathworldPlanetmath.  Cf. angle bisector as locus.

Title quadrant
Canonical name Quadrant
Date of creation 2014-12-16 22:42:51
Last modified on 2014-12-16 22:42:51
Owner Mathprof (13753)
Last modified by pahio (2872)
Numerical id 14
Author Mathprof (2872)
Entry type Definition
Classification msc 51N20
Synonym quarter-plane
Related topic RightAngle
Related topic ConvexAngle
Related topic Octant
Defines 1st quadrant
Defines 2nd quadrant
Defines 3rd quadrant
Defines 4th quadrant