1. MEASURING LENGTH Page 42 Length
· Define length and congruent.
· Identify and use the Segment Addition Postulate.
In defining the length of a segment, we will use a
number line, which is like a ruler. A number line is
a line that has been set up to correspond with the
real numbers.
The coordinate of a point on a number line is a real number.
In the illustration above, 5 is the coordinate of point A and 4
is the coordinate of point B.
How would you find the distance between points A and B?

2. Length of AB (1.2.1)
Let A and B be points on a number line, with coordinates
a and b. Then the measure of AB, which is called its
length, is |a - b| or |b - a|.
EXAMPLES
Find the measures (lengths) of AB, AT, AND TB on the
number line.

3. Congruent ( ≅ ) Segments
Congruent figures are figures that are the same size and
shape.
Which segments are congruent?
Segment Congruence Postulate (1.2.2) (BLUE)
If 2 segments have the same length as measured by a fair
ruler, then the segments are ≅. Also, if 2 segments are ≅,
then they have the same length as measured by a fair ruler.

4. Segment Addition Postulate (1.2.3)
If point R is between points P and Q on a line, then
PR + RQ = PQ.
EXAMPLE
The towns of Squidward, Patrick, and Plankton are located
along a straight road. Patrick is between Squidward and
Plankton. The distance from Squidward to Patrick is 13 miles
more than 5 times the distance from Patrick to Plankton. The
distance Squidward to Plankton is 103 miles. Find the distance from Squidward to Patrick and from Patrick to Plankton.

5. EXIT TICKET
All that separates you from 4th period and the long weekend is...