quadrantQuadrant2004-10-04 16:22:222007-04-09 21:07:13Definition1st quadrant2nd quadrant3rd quadrant4th quadrant% this is the default PlanetMath preamble. as your knowledge
% of TeX increases, you will probably want to edit this, but
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\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{amsfonts}
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%\usepackage{psfrag}
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%\usepackage{graphicx}
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% define commands hereThe $x$- and $y$-axes \PMlinkescapetext{divide} the $xy$-plane in four right-angle domains which are called the {\em quadrants} of the plane. \,They are numbered going round the origin in anticlockwise direction so that
$$\{(x,\,y) \mid x > 0, \,\,y > 0\}$$
is the {\em first quadrant},
$$\{(x,\,y) \mid x < 0, \,\,y > 0\}$$
the {\em second quadrant}, and so on.
Naturally, one can speak of the quadrants of the complex plane, too.