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1.2 Linear Measure and Precision. Objectives:. Measure segments and determine accuracy of measurement. Compute with measures.
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Objectives: • Measure segments and determine accuracy of measurement. • Compute with measures.
A line segment or segment AB (or BA) consists of the endpoints A and B, and all points on AB that are between A and B. Line segments have exact measures but can only be as precise as the smallest unit of the measuring device. Segments Segment CD D C l B A Line lor AB
The precision of any measurement depends on the measuring tool. The measurement should be within 0.5 unit of the measure. Thus, if AB is measured in inches and is 2” long, its precision is 1.5” to 2.5”. Precision l B A Line lor AB
A B C Measures • Measures are real numbers, thus all arithmetic properties can be applied. • If we have a line segment divided into parts, then by applying a relationship called betweenness of points we know the measure of each segment added together equals the measurement of the entire segment. AB + BC = AC
D A B C Congruent Segments • When segments have the same measure, they are said to be congruent (). • is read “is congruent to.” Slashes on the line segments also indicate the segments are congruent. • AB CD
More About Congruency • Note, when we are discussing segments we draw a line over the endpoints, AB, but when we are discussing the measure of segments we simply write the letters. Likewise, we must also be sure that when we are comparing segments we use the congruent sign, but when we are comparing their measures we use an equal sign. Never intermix the two symbols. AB CD segments AB = CD measures
Assignment: • Geometry Pg. 17, #12 – 18, 22 – 39 • Pre-AP Geometry Pg. 17 – 19, #12 – 39 & 50