Segments and their Measure
Section 1.5
RAY : part of a line with one end point
Name a ray by first naming the end point and then
naming one other point on the ray and then drawing the symbol above the name.
Symbol:
Example:
The name of our example is AB
or AC or
AD
In
our example A is the endpoint and the ray extends forever in the B direction.
Note
that the endpoint is always named first and the arrow is
over the other point on the ray.
SEGMENT: part of a line that has two endpoints.
Name
a segment by naming the two endpoints in any order and then drawing the symbol
above the two endpoints.
Symbol:
Example:
In the line
AB there are several line
segments: AB and
AC and
AD and
BC and BD
and CD and
DA and . . .
Segments
of equal length are congruent segments.
Tick marks are used to show
congruence.
You
can write " ED
is congruent to
FD" by writing ED 
FD
The
length of the segment ED, written ED,
is the distance from E to D.
Count the length of JK
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Betweenness:
If XY + YZ
= XZ, then the point Y is between points X and Z.
Remember:
XY means the distance from X to Y
Segment Addition:
If point Y is between points X and Z, then XY + YZ
= XZ
A conditional statement can be written in the form "if P, then
Q".
A conditional statement may be true or false
Example:
If today is July 4, then it is Independence Day in
the
It is Independence Day in the
If all the vertices of a
network are even, then the network is traceable.
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Truth Table for
Conditionals |
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Hypothesis (If) |
Conclusion
(then) |
Statement |
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A |
B |
A > B |
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true |
true |
true |
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true |
false |
false |
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false |
true |
true |
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false |
false |
true |