1. 1.21.2 Use Segments and Congruence
Bell Thinger
1. Solve 3x + 5 + 2x – 4 = 36.
ANSWER 7
2. Find three cities on this map that appear to be
collinear.
Chicago, Bloomington, SpringfieldANSWER

2. 1.2

3. 1.2

4. 1.2Example 1
Measure the length of ST to the nearest tenth of a
centimeter.
SOLUTION
Align one mark of a metric ruler with S. Then estimate
the coordinate of T. For example, if you align S with 2,
T appears to align with 5.4.
Use Ruler Postulate.ST = 5.4 – 2 = 3.4
The length of ST is about 3.4 centimeters.ANSWER

5. 1.2

6. 1.2Example 2
SOLUTION
Maps
The cities shown on the map
lie approximately in a straight
line. Use the given distances
to find the distance from
Lubbock, Texas, to St. Louis,
Missouri.
Because Tulsa, Oklahoma, lies between Lubbock and
St. Louis, you can apply the Segment Addition
Postulate.
LS = LT + TS = 380 + 360 = 740
The distance from Lubbock to St. Louis is
about 740 miles.
ANSWER

7. 1.2Guided Practice
3. Use the Segment Addition Postulate to find XZ.
In Exercises 3 and 4, use
the diagram shown.
ANSWER 73
In the diagram, WY = 30. Can you use the Segment
Addition Postulate to find the distance between
points W and Z? Explain your reasoning.
4.
No; W is not between X and Z.ANSWER

8. 1.2Example 3
Use the diagram to find GH.
Use the Segment Addition Postulate to write an
equation. Then solve the equation to find GH.
SOLUTION
Segment Addition Postulate.
Substitute 36 for FH and 21 for FG.
Subtract 21 from each side.
21 + GH=36
FG + GH=FH
=15 GH

9. 1.2

10. 1.2Example 4
SOLUTION
To find the length of a horizontal
segment, find the absolute
value of the difference of the
x-coordinates of the endpoints.
Plot J(– 3, 4), K(2, 4), L(1, 3), and M(1, – 2) in a coordinate
plane. Then determine whether JK and LM are
congruent.
Use Ruler Postulate.JK = 2 – (– 3) = 5

11. 1.2Example 4
SOLUTION
Plot J(– 3, 4), K(2, 4), L(1, 3), and M(1, – 2) in a coordinate
plane. Then determine whether JK and LM are
congruent.
To find the length of a vertical
segment, find the absolute
value of the difference of the
y-coordinates of the endpoints.
Use Ruler Postulate.LM = – 2 – 3 = 5
JK and LM have the same length. So, JK LM.=~
ANSWER

12. 1.2Guided Practice
5. Use the diagram to find WX.
107ANSWER
No.ANSWER
Plot the points A(– 2, 4), B(3, 4), C(0, 2), and D(0, – 2) in
a coordinate plane. Then determine whether AB and
CD are congruent.
6.

13. 1.2Exit Slip
2. Find CE.
ANSWER 22
1 in.ANSWER 8
3
1. Measure AB to the nearest inch.
8
1

14. 1.2Exit Slip
ANSWER No, FG = 5 and HJ = 4
4. Find KL
ANSWER 7
3. Plot the points F(–3, 5), G(2, 5), H(3, 1), J(3, –3)
in a coordinate plane. Are FG and HJ
congruent? Explain.

15. 1.2
Homework
Pg 12-14
#14, 17, 32, 33, 35