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Using a Protractor

Date: 8/15/96 at 18:27:35
From: Anonymous
Subject: Using a Protractor

How do I measure angles using a protractor? My protractor has two
sets of numbers, one above the other. How do I know which set to use?

Date: 8/30/96 at 17:2:53
From: Doctor James
Subject: Re: Using a Protractor

Since you can measure angles from either side of the protractor, they
have given you two sets of numbers. One set of numbers measures from 
the left side, the other measures from the right side.  The way to 
figure out which to use is this:

Put the bottom marking (where it will say either 0 or 180) on one leg
of the angle, such that the other leg of the angle is going through 
the curved part of the protractor. So now you will know that the angle 
is one of the two angles it tells you. However, one of the two sets 
will tell you that the first leg is at 0 degrees; this is the set you 
want. You can check it because as the two legs get closer together, 
the angle should get smaller.

-Doctor James,  The Math Forum
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Associated Topics:
Elementary Geometry
Elementary Two-Dimensional Geometry
Middle School Geometry
Middle School Two-Dimensional Geometry

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