Measurement of Segments and Angles

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Section 1.2

• Measurement of Segments and Angles

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Objectives

• After studying this section, you will be able to
• Measure segments
• Measure angles
• Classify angles by size
• Name the parts of a degree
• Recognize congruent angles and segments

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Measuring Segments

• We measure segments by using such instruments as
  rulers or metersticks
• We may use any convenient length as a unit of
  measure
• Some of the units that are currently in use are
  inches, feet, yards, millimeters, centimeters,
  and meters

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Measuring Angles

• Angles are commonly measured by means of a
  protractor
• We measure angles in degrees
• The measure, or size, of an angle is the amount
  of turning you would do if you were at the
  vertex, looking along one side, and then turned
  to look along the other side
• See book Page 10

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Classifying Angles by Size

• An acute angle is an angle whose measure is
  greater than 0 and less than 90
• A right angle is an angle whose measure is 90
• An obtuse angle is an angle whose measure is
  greater than 90 and less than 180
• A straight angle is an angle whose measure is 180
  ( A straight line)

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Acute Angles
Right Angles
Obtuse Angles
Straight Angles
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Parts of a Degree

• Each hour of the day is divided into 60 minutes,
  and each minute is divided into 60 seconds
• Each degree is divided into 60 minutes, and each
  minute is divided into 60 seconds

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Congruent Angles and Segments

• Congruent angles are angles that have the same
  measure
• Congruent segments are segments that have the
  same length

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We often use identical tick marks to indicate
congruent angles and segments. The diagrams
indicate three pairs of congruent parts, can you
name them?
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Practice Problems
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Recap/Assignment

• What are the four types of angles?
• How many minutes are in a degree?
• What does congruent mean?
• Page 14 2-8, 9, 14-20 evens
• Quiz Tomorrow!!!!
• Make sure you have your notes