6th Grade Math Textbook, Fundamentals

Lesson 9-2 for exercise sets. &KDSWHU 

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Estimate the measure of each angle. Classify each
as acute, right, obtuse, or straight.
Then use a protractor to find the actual measure.

5.Name three times at which the hands of a clock form an acute angle.

6.Discuss and Write The angle of incline for a loading ramp is

often about 20°. What might occur if the angle were greater?

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You can use a protractorto find the degree measure of an angle.

mark at 110° point of protractor

point marked for vertex

To measure an angle:

Place the protractor so that its zero line rests

along one ray of the angle, called the base ray,

and its center mark is at the vertex of the angle.

Find the 0 on the scale where the base ray,

BC, crosses the protractor.

Follow along that scale to the point where

the other ray, BA, crosses the protractor.

The number at that point is the measure

of the angle.

To draw an angle:

Mark a point for the vertex of the angle.

Position the center mark of the protractor at

the vertex. Mark another point at 0 on either

scale of the protractor. Draw a ray from the

vertex through the point at 0.

To draw a 110° angle, follow along the scale

where the ray crosses the protractor to 110.

Mark a third point there. Draw a second

ray from the vertex to that point.

You can use a protractor and a straightedge to draw an angle

of a given measure.

At different times of day the hour and minute hands

of a clock form angles with different measures.

The minute hand of an analog clock rotates

360° every hour. It rotates one twelfth of 360°,

or 30°, every five minutes.

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