Longitude Degrees at the Equator

Date: 09/09/97 at 12:03:08
From: Motts Parrinello
Subject: Distance in miles between longitude degrees at the equator

Dear Dr. Math,

What is the distance in miles between degrees of longitude at the
equator ?

Is it the circumference of the earth divided by 360 degrees? 
If so, how do I find the circumference or diameter so I can 
multiply by 3.14 ?

Thank you,

Motts Parrinello

Date: 09/09/97 at 12:57:36
From: Doctor Rob
Subject: Re: Distance in miles between longitude degrees at the 
equator

Yes, it is the circumference of the Earth divided by 360.  
The answer is exactly 60 nautical miles, by definition.  

Since one nautical mile is 1.150777 statute miles, your answer is 
69.04663 miles. Multiply by 360 to get the circumference of the earth, 
then divide by Pi to get the diameter, and divide again by 2 to get 
the radius of the Earth.

-Doctor Rob,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/