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To Measure an Angle
Place the protractor's center on the
angle's vertex. Place the 0° mark
on one side of the angle. Read the
measure where the other side of
the angle crosses the protractor. |
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| How do you use a protractor? |
You
can use a protractor to measure and draw
angles. |
| a. |
Trace each angle and
extend its sides. Follow the directions at the right to measure each angle. |
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| The measure of |
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is 56°. |
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| To Draw an Angle of 140° |
| Draw |
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. Be sure to label the |
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| endpoint
T.
Place the protractor's |
| center
on T.
Line up |
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with the |
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| 0° mark. Place a point at 140°. |
| Label it W. Draw |
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| b. |
There are two scales of numbers on a protractor.
How did you decide which one to use? |
| c. |
Follow the directions at the right to draw an
angle with each measure. |
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| The measure of |
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is 140°. |
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How can you classify angles? |
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An
acute
angle has
a measure between
0 ° and 90°. |
A
right
angle has
a measure of 90°.
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An
obtuse angle has
a measure between
90° and 180°.
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A
straight angle has
a measure of 180°.
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Talk About It |
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1. |
Find an example of each of the four types of angles
in
your classroom. |
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