Download 1.3 Segments and Measures

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1.3 Segments and
Measures
Geometry
Week of 9/12/16
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Today
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You will be able to measure segments and determine accuracy
of measurement.
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You will be able to use the Distance Formula to measure
distances.
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Some Vocab
 Unlike
lines, we can measure segments because they
have 2 endpoints
 Ruler
Postulate: The points on a line can be matched one
to one with the real numbers.
 Coordinate: The
real number that corresponds to a point
is the coordinate of the point.
 Distance: The
distance between points A and B, written as
AB, is the absolute value of the difference between the
coordinates of A and B.
 AB is also called the length of AB
 Notation: If the length of AB is 3 units, we write
AB = 3
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Example 1 - Measurement
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Find the length of each segment or object.
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Betweenness
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When three points lie on a line, you can say that one of them
is between the other two.
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Example:
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Not an Example:
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Segment Addition Postulate
 If
B is between A and C, then AB+BC = AC. OR
 If
AB+BC = AC, then B is between A and C.
 Example
2: : If K is between T and U and KT = 5 and
KU = 21, find TU. Draw a picture.
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Example 3
If
Q is between P and R and PR = 25 and
QR = 18, find PQ.
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Example 4
If
DT = 60, Find the value of x. Then find
the value of DS and ST.
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Day 1 Homework
pages
21 and 22 problems 13-18 all,
23-33 odds
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Congruence
Two
segments that have the same
length are congruent segments.
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The Distance Formula
-d is the distance between two points A
and B
-can say d is AB
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Example 5
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Find the length of the line segment whose endpoints are (-3, 4) and
(5,4).
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Example 6
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Find the distance between the points (-4,-5) and (1,-2).
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Example 7a
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Use the distance formula to decide whether JK ≅ KL.
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a. J(3, -5), K(-1, 2), L (-5, -5)
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Example 7b
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J(0, -8), K(4, 3), L (-2, -7)
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Day 2 Homework
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page 22 problems 34 - 43 all