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A
protractor
is a clear plastic device to measure angles from
0 to 180 degrees.
You can use
a protractor to
measure an angle in degrees.
 How do I measure angles using a
protractor? There
are two sets of numbers, so you can measure angles from either side
of the protractor.
To decide which scale to use,
look at the angle you're measuring.
If it is greater than a right angle (more than ninety degrees) then
use the scale that has numbers greater than 90. If the angle is acute (measures less than 90 degrees), use the scale which
has numbers less than 90.
Example:
right
angle
 A right angle measures
90 degrees. Measure an angle by
measuring the distance between its sides.
Place the
protractor on the angle so that the center point is on the vertex
and the zero line is along one side of the angle. Follow the scale
beginning at zero and read the measure of the angle where the other
side of the angle intersects the scale on the protractor.
Example:
acute
angle
 An acute angle is
less than 90 degrees.
Example:
obtuse
angle
An obtuse angle is
greater than 90 degrees.
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