Transcript 1.3 Measuring Segments - Cardinal O'Hara High School

Day Problems 9/12/12
1. Name the intersection
of plane AEH and
plane GHE.
2. What plane contains
points B, F, and C?
3. What plane contains
points E, F, and D?
1.3 Measuring Segments 9/12/12
• Postulate 1.5 – Ruler Postulate
– Every point on a line can be paired with a real number.
– The real number that corresponds to a point is called the
coordinate of the point.
– Allows you to measure lengths of segments and will
allow you to find the distances between points.
• The distance between points A and B is the
absolute value of the difference of their
coordinates.
Measuring Segment Lengths
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•
•
•
What is ST?
What is SV?
What is UV?
What is TV?
Measuring Segment Lengths
•
•
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•
ST = | -4 – 8 | = | -12| = 12
SV = |-4 – 14 | = | -18| = 18
UV = | 10 – 14| = | -4| = 4
TV = |8 – 14| = | -6 | = 6
Postulate 1.6 Segment Addition Postulate
• If three points A, B, and C are collinear and B is
between A and C, then AB + BC = AC.
Using the Segment Addition Postulate
• If EG = 59, what are EF and FG?
EF + FG = EG
(8x – 14) + (4x + 1) = 59
12x – 13 = 59
12x = 72
x=6
EF = 8(6) – 14 = 34
FG = 4(6) + 1 = 25
Congruent Segments
Comparing Segment Lengths
• The midpoint of a segment is a point that
divides the segment into two congruent
segments.
• A point, line, ray, or other segment that
intersects a segment at its midpoint is said to
bisect the segment.
– The point, line, ray, or segment is called a segment
bisector.
A
M
B
Using the Midpoint
• Q is the midpoint of PR. What are PQ, QR, and PR?
• Find x.
6x – 7 = 5x + 1
x–7=1
x=8
Find PQ and QR.
PQ = 6x – 7
=6(8)–7
= 41
Find PR.
PR = PQ + QR = 41 + 41 = 82.
More Practice!!!!!
• Classwork – Textbook p. 24 #7 – 21 ODD.
• Homework – Textbook p. 24 #8 – 22 EVEN.