Transcript Section 2
Lesson 1-2 Linear Measure and Precision 5-Minute Check on Lesson 1-1 Transparency 1-2 Refer to the figure for questions 1 through 5. 1. Name three collinear points. 2. What is another name for AB? 3. Name a line in plane Z. 4. Name the intersection of Planes Z and W. 5. How many lines are in plane Z? 6. 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. Transparency 1-2 5-Minute Check on Lesson 1-1 Refer to the figure for questions 1 through 5. 1. Name three collinear points. A, T, B 2. What is another name for AB? 3. Name a line in plane Z. AT or TB AT or l 4. Name the intersection of Planes Z and W. 5. How many lines are in plane Z? 6. AB 2 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. 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 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. 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. a. Find the length of Answer: 18 mm 2 ¼ ½ ¾ 3 ¼ ½ ¾ 4 Precision Precision – ½ the smallest unit of measure on the measuring device 70°F Smallest Unit of Measure = 1/8 th inch Precision = (1/8)/2 = 1/16 th inch 60°F String Length is 2 ¼ ± 1/16 or between 2 3/16 and 2 5/16 inches long 50°F 1 ¼ ½ ¾ 40°F 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 Answer: The precision is be inches to inch. inch. The measurement could inches. PRECISION Find the precision for each measurement. Explain its meaning. a. 88 millimeters Answer: The precision is 0.5 millimeter. The measurement could be 87.5 millimeters to 88.5 millimeters. b. Answer: The precision is could be inch. The measurement inches to inches. Whole = Sum of its Parts Any distance can be broken into pieces and the sum of those pieces is equal to the whole distance 14 11 A B 6 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 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. Find x and ST if T is between S and U, ST = 7x, SU = 45, and TU = 5x – 3. 5x – 3 U 7x T S Substitute known values. Add 3 to each side. Simplify. Divide each side by 12. Simplify. c. Find a and AB if AB = 4a + 10, BC = 3a – 5, and AC = 19. 3a – 5 4a + 10 A Answer: a = 2, AB = 18 B C Summary & Homework • Summary: – 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