How Does a Protractor Work?
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Measures Angles
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Protractors are used to measure angles. They are usually used in a school setting when studying geometry. To measure an angle you must take the protractor and place the hole in the center over the middle point or the vertex of the angle you want to measure. Then you line up the 0 at the left end of your protractor with one side of the angle. Make sure it is straight. The other side of the angle should clearly be seen and it should pass by a number on your protractor. This is the number you need to determine the degree of the angle of that particular problem.
Draws Angles
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In geometry you may also be asked to create some angles. You can do this by first drawing a straight line. Place a dot on each end of the line and use one as your starting point. Place that dot under the hole in the middle of the protractor. Place a dot next to the angle number that your problem needs to be. If you need a 90 degree angle you would put a dot at the 90. Then draw a line from your point under the protractor to the point where the 90 was. Now you have your angle.
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As a Ruler
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Most protractors have a ruler across the bottom of them. That would be on the straight edge. If your protractor doesn't have a ruler on the bottom you should consider getting one that does. They are extremely useful and can even guide you when you want to make your own angles. You can use the protractor to draw dots where you need your angle to be and then use the ruler side to make the angles as long or short as you need them to be. The ruler will also help you keep a straight edge when drawing the angles.
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Resources
- Photo Credit Lewis Chaplin
