Linear Measure and
Precision
Section 1-2
segment – a part of a line that
consists of 2 points, called
endpoints, and all the points
between them
A
C
AC refers to the segment
AC
AC refers to the length of AC
Measuring Line Segments
• Unlike a line, a line segment, or segment, can
be measured because it has two endpoints.
The length of a segment is only as precise as
the smallest unit on the measuring device.
• The precision of any measurement depends on
the smallest unit available on the measuring
tool. The measurement should be precise to
within 0.5 unit of measurement.
Betweenness of Points
• For any two real numbers a and b, there
is a real number n between a and b such
that a < n < c.
a
n
c
• Point n is between points a and c iff a, n,
and c are collinear and an + nc = ac
Constructions
• Constructions are methods of
creating geometric figures without
the benefit of measuring tools.
• Generally, only a pencil,
straightedge, and compass are used
in constructions.
Probability and Segment Measure
• Probability (P) of an event =
number of favorable outcomes
total number of possible outcomes
2 mm
A
B
6 mm
2 mm
C
D
• The probability that a point randomly selected
on the number line is contained in AB is
2
1
or
10
5