Circle Graphs

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Circle Graphs

• Lesson 11.2
• August 18, 2008
• 8th Grade Pre-Algebra

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• A circle graph shows how the parts are related to
  the whole.

Part
3

• In order to make a circle graph for any
  information, you have to find the degree
  measurement of the central angle for each piece
  of the circle graph.
• The central angle is an angle made from the
  center of the circle graph, giving each piece its
  size.

Central angle
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Survey. What is your favorite class in middle
school?
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• Lets make a circle graph of our class
  information.
• How many pieces will your circle graph have?
• What piece of the circle graph will be the
  largest?
• What piece of the graph will be the smallest?

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• To make the circle graph, you will need
• Calculator
• Compass (to make a perfect circle)
• Protractor
• Straightedge

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• Steps to make a circle graph
• Find the central angle of each piece of the pie.
  To find the central angle, you multiply the
  fraction, decimal, or percent by the total number
  of degrees in a circle, which is_____.
• If one piece of the pie is supposed to be 30
  of the whole thing, you want to find out what 30
  (or 1/3) of the whole, or 360 degrees is. Write
  that equation here

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• Steps to make a circle graph (continued)

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• Steps to make a circle graph (continued)
• Use your compass to make a perfect circle
• Using your straightedge, draw a radius anywhere
  on your circle. This is the start of your first
  piece of the pie.
• Use your protractor to measure the central angle
  for your first piece. Draw the next line.
• Continue around the circle until all pieces are
  finished.
• You shouldnt have any gaps or overlaps when your
  finished!

Step 3
Step 4
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Lets practice!
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Check it!