Class : Geometry
Topic : Segments, rays, and distance
Aim : What are some definitions involving lines and line segments?
Objectives :
1) Students will be able to describe what is a line segment and a ray.
HW# 002:
Date : Monday September 10 th , 2012
Do Now : The intersection of two figures is the set of points that are in both figures.
What is the intersection of the two planes shown at right?
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PROCEDURE :
Write the Aim and Do Now
Get students working!
Take attendance
Go over the Do Now
If we examine part of a line with endpoints, then what figure do we have?
_________________________
Definition : A line segment is a set of points consisting of two points on a line called endpoints and all the points on the line between the endpoints.
How can we denote a line segment? _________________
Definition : A ray is part of a line that consists of a point on the line, called an endpoint, and all the points on one side of the endpoint.
How can we name a ray?__________________________
Definition : Opposite rays are two rays of the same line with a common endpoint and no other point in common.
In the picture at right, what are two opposite rays?
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For which of the following figures could we determine a length?
A) Point P
B) Line AB
C) Ray AB
D) Line Segment AB
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Definition : The length or measure of a line segment is the distance between its endpoints. AB represents the measure of
Definition : Congruent segments are segments that have the same length.
How could we denote that line segments AB and CD are congruent?
How could we denote that line segments AB and CD have the same length?
Definition : The midpoint of a segment is the point of that line segment that divides the segment into two congruent segments. If C is the midpoint of line segment AB, what statement of congruence can we make?
____________
What statement of equality can we make?
The bisector of a line segment is any line or subset of a line that intersects the segment at its midpoint.
Question :
AB
What is the length of AB, if line l is the segment bisector and AO = 6 units?
Choices:
A. 13 units
B. 6 units
C. 12 units
D. 14 units
Exercise : B is between A and C, with AB
 x , BC
A) The value of x
 x

6 , and AC

24 . Find
B) BC
The above exercise illustrates the Segment Addition Postulate . A postulate is a statement whose truth is accepted without proof.
The Segment Addition Postulate states that if B is between A and C, then AB

BC

AC .

Continue answering the following questions:
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