Radians

Date: 9/2/96 at 22:52:58
From: Mohd Nasir Mahmud
Subject: Radians

Dear Sir,

Could you tell me why pi radians = 180 degrees?

Date: 10/24/96 at 16:5:50
From: Doctor Jaime
Subject: Radians

This is an immediate consequence of the definition of radians and 
degrees.  In fact 1 radian is defined as the central angle subtended 
by the arc of length 1 on a unit circle.  1 degree is the central 
angle subtended by (1/360)th of the circumference of a unit  circle. 

This measure dates back to the Babylonians, who used a base 60 
number system. Since the circumference of the unit circle is 2 Pi, 
it follows that there are 2 Pi radians in 360 degrees, or 
Pi radians = 180 degrees.

-Doctor Jaime,  The Math Forum
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