Using X and Y to Represent the Axes

Date: 9/29/95 at 17:38:5
From: Fred Johnson

Shane asks, "Why are the axes on a graph x and y and not any other 
letter in the alphabet?"

Nate asks, "Why is the y-axis generally vertical and the x-axis 
generally horizontal?"

Thanks for taking these questions,
Fred Johnson

Date: 11/5/95 at 15:44:20
From: Doctor Rob
Subject: Re: (no subject)

Hi Fred, Nate and Shane.  

Both questions deal with mathematical conventions.  No, not 
gatherings of mathematicians, but rules or practices that over 
time have developed in the mathematical community.  In general, 
mathematicians use symbols from the end of the alphabet to  
signify variables and symbols from the beginning of the alphabet 
to signify constants.  Similarly, in 2-variable situations x is 
usually the independent variable and y the dependent variable.  
There really is no reason for these conventions, and it's 
important to realize that you are free to use them or not when 
doing mathematics, as long as you  define what represents what.  
Take care, and write back if you have any additional questions.

-Doctor Rob,  The Geometry Forum