Points, Lines, and Line Segments A Geometry presentation by Olivia Ingram

Points Points are places on a number line, often identified by a single dot “•” and are named an alphabetical letter. • A • B

Lines come in three forms: Ray Line Line Segment • • • •

Measuring Points and Line Segments On a number line, you can easily measure the distance between two points. A B • • 1 2 3 4 5 6 7 8 Two ways to solve: Count the spaces between the points Subtract the smallest number from the largest number 4 spaces between points = 4 6 – 2 = 4

Measuring Points and Line Segments You may need to measure line segments whose points lie on both positive and negative numbers, which may throw you for a loop, but is just as simple. A B • • -4 -3 -2 -1 1 2 3 4 When counting, the negative and positive symbols make no difference Do not solve this by subtraction. Ignoring the negative and positive symbols, add the points together: = 2 1 + 1 = 2

Measuring Points and Line Segments Once you know how to measure the distance between points on a line segment, measuring more than two points on a line segment should be a piece of cake.

Answering Equations You should write the measurement of the distance between points using letters and symbols. A B • • 1 2 3 4 5 6 7 8 = AB

Points, Lines, and Line Segments: Practice Problems • • -4 -3 -2 -1 1 2 3 4 X Y • • 1 2 3 4 5 6 7 8 9 A C • • • -4 -3 -2 -1 1 2 3 4

Points, Lines, and Line Segments: Practice Problem Answers 1) AB = 5 2) XY = 2 3) AC = 5