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

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 Click the mouse button or press the Space Bar to display the answers.

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 Click the mouse button or press the Space Bar to display the answers.

Objectives Measure segments and determine accuracy of measurement Compute with measures Sum of the parts equals the whole

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

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

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

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

Precision Precision – ½ the smallest unit of measure on the measuring device 1 2 3 4 ½ ¼ ¾ 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

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

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

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 = 11 + 14 + 6

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

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

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

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