Order of Quadrant Numbers

Date: 10/21/2002 at 08:04:33
From: Robin Murphy
Subject: Quadrant numbers

Why are quadrants numbered that way?

Date: 10/21/2002 at 12:34:50
From: Doctor Peterson
Subject: Re: Quadrant numbers

Hi, Robin.

It's hard to know "why" without being able to ask whoever first did 
it, but my understanding is that the quadrants are numbered in the 
order an angle in standard position passes through them as the angle 
increases - that is, counterclockwise starting at the x axis. If you 
ask why standard position is what it is, that's even harder to answer 
with certainty, but someone just felt that the x-axis (lying down 
flat) made a good starting position, and rising from there was a good 
direction to start.

If you have any further questions, feel free to write back.

- Doctor Peterson, The Math Forum
  http://mathforum.org/dr.math/