1. Linear Measure and Precision
Lesson 1-2
Linear Measure and Precision

2. 5-Minute Check on Lesson 1-1
Transparency 1-2
5-Minute Check on Lesson 1-1
Refer to the figure for questions 1 through 5.
Name three collinear points.
What is another name for AB?
Name a line in plane Z.
Name the intersection of Planes Z and W.
How many lines are in plane Z?
Three lines are coplanar. What is the greatest number of intersection point that can occur?
Standardized Test Practice: A 2 B 3 C 4 D 5
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3. 5-Minute Check on Lesson 1-1
Transparency 1-2
5-Minute Check on Lesson 1-1
Refer to the figure for questions 1 through 5.
Name three collinear points.
What is another name for AB?
Name a line in plane Z.
Name the intersection of Planes Z and W.
How many lines are in plane Z?
Three lines are coplanar. What is the greatest number of intersection point that can occur?
A, T, B
AT or TB
AT or l AB 2
Standardized Test Practice: A 2 B 3 C 4 D 5
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4. Objectives Measure segments and determine accuracy of measurement
Compute with measures
Sum of the parts equals the whole

5. Vocabulary Line Segment – has two end points and can be measured
Precision – is equal to one-half the smallest unit on the measuring tool
Congruent – when segments have the same measure, they are congruent ()
Equal – numbers (variable and equations) and measurements of things are equal if the have the same values

6. Answer: is about 42 millimeters long.
Find the length of .
The long marks are centimeters, and the shorter marks are millimeters. There are 10 millimeters for each centimeter.
Answer: is about 42 millimeters long.
Example 2-1a

7. Answer: is about 5 centimeters long.
Find the length of .
The ruler is marked in centimeters. Point R is closer to the 5-centimeter mark than to 4 centimeters.
Answer: is about 5 centimeters long.
Example 2-1b

8. a. Find the length of
Answer: 18 mm
Example 2-1c

9. Precision
Precision – ½ the smallest unit of measure on the measuring device 1 2 3 4
40°F
50°F
60°F
70°F
Smallest Unit of Measure = 1/8 th inch
Precision = (1/8)/2 = 1/16 th inch
String Length is 2 ¼ ± 1/16 or
between 2 3/16 and 2 5/16 inches long
Smallest Unit of Measure = 2°F
Precision = (2°F)/2 = 1°F
Temperature is 60°F ± 1°F or
between 59°F and 61°F

10. Find the precision for 32¾ inches. Explain its meaning.
The measuring tool is divided into -inch increments. Thus,
the measurement is precise to within inch.
Answer: The precision is inch. The measurement could
be inches to inches.
Example 2-3a

11. PRECISION Find the precision for each measurement. Explain its meaning.
a. 88 millimeters b.
Answer: The precision is 0.5 millimeter. The measurement could be 87.5 millimeters to 88.5 millimeters.
Answer: The precision is inch. The measurement could be inches to inches.
Example 2-3c

12. Whole = Sum of its Parts
Any distance can be broken into pieces and the sum of those pieces is equal to the whole distance 11 14 6 A B C D 32
The whole length, AD, is equal to the sum of its parts, AB + BC + CD
AD = AB + BC + CD
32 =

13. Point M is between L and N.
Find LM.
LM is the measure of .
Point M is between L and N.
Sum of parts whole
Substitution
Subtract 2.6 from each side.
Simplify.
Answer: is 1.4 centimeters long.
Example 2-4a

14. Substitute known values.
Find x and ST if T is between S and U, ST = 7x, SU = 45, and TU = 5x – 3. U T S
5x – 3 7x
Substitute known values.
Add 3 to each side.
Simplify.
Divide each side by 12.
Simplify.
Example 2-4d

15. c. Find a and AB if AB = 4a + 10, BC = 3a – 5, and AC = 19.
Answer: a = 2, AB = 18
Example 2-4h

16. Summary & Homework Summary: Homework:
The precision of any measurement depends on the smallest unit available on the measuring device
The measure of a line segment is the sum of the measure of its parts WHOLE = SUM OF PARTS
Homework:
pg 16-17; 5, 8, 25, 29-31