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How to use a protractor

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The "vertex" of the angle lined up correctly underneath the protractor; angles, protractor, obtuse angle, acute angle, 70 degrees, 110 degrees;

Step 1 – Line protractor up with angle

On a protractor the angles are marked with lines which come together in the middle of the line reading 0 degrees. To measure an angle, the “vertex” of the angle must be placed underneath this point.

The base of the angle on the 0 degree line; angles, protractor, obtuse angle, acute angle, 70 degrees, 110 degrees;

Step 2 – Line up one side of angle with 0° line 

Ensure that the base of the angle rests on the line reading 0 degrees.

The diagonal line matches up with the 70/110 degree line; angles, protractors

Step 3 – Read angle from protractor

The other side of the angle will now line up with one of the degree markers on the protractor.

Top (left to right): 18 degree angle, 45 degree angle and 33 degree angle. Bottom (left to right): 88 degree angle, 22.5 degree angle and 7 degree angle This will tell you what degree the angle is.
Wonkee Donkee says "Remember to read the protractor in the correct direction. Otherwise you will read the angle incorrectly."
A protractor showing that only every tenth number is shown; blue, semi circle, protractor 180 degree Protractors traditionally have every degree marked on them. However, usually only every tenth degree has its number marked next to it (i.e.: 10, 20, 30 etc).