14 MEASURING SEGMENTS AND ANGLES

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1-4 MEASURING SEGMENTS AND ANGLES

• OBJ to find the lengths of segments and
  measures of angles

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POSTULATE 1-5

• RULER POSTULATE the length of a segment AB can
  be found by subtracting the endpoints of the
  segment and finding the absolute value of the
  answer.
• AB l a-b l

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APPLYING THE RULER POSTULATE

• Find the lengths of AB, BC, CD, DE, BD

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CONGRUENT SEGMENTS

• Two segments with the same length are said to be
  congruent

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POSTULATE 1-6

• SEGMENT ADDITION POSTULATE
• If three points A, B, C are collinear and B is
  between A and C, then
• AB BC AC

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SEGMENT ADDITION POSTULATE

• If DT60, find the value of x. Then find DS and
  DT.

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MIDPOINT OF A SEGMENT

• A point that divides a segment into two congruent
  segments.
• M is the midpoint of AB.
• A midpoint, or any line, ray, or other segment is
  said to bisect the segment

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PROBLEM SOLVING USING THE MIDPOINT OF A SEGMENT

• C is the midpoint of AB. Find AC. CB, and AB.

A
B
C
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ANGLES

• Angle formed by two rays with the same
  endpoint. The rays are the sides. The endpoint
  is the vertex.

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NAMING ANGLES

• Name the angles

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Classifying angles

• Angles are classified by their measure.
• Acute Angles angles that are greater than 0
  but less that 90.

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RIGHT ANGLES

• An angle whose measure 90

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OBTUSE ANGLES

• An angle whose measure is greater than 90 but
  less than 180

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STRAIGHT ANGLES

• An angle whose measure is to 180

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POSTULATE 1-8

• ANGLE ADDITION POSTULATE

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ADJACENT ANGLES

• Coplanar angles
• Share a common vertex
• Share a common side
• No common interior points

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CONGRUENT ANGLES

• CONGRUENT ANGLES Angles with the same measures