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U8-8 Notes Transversals and Parallel Lines
Name:__________________________
Date:__________________Period:____
Vocabulary – Add each of the following to your vocabulary sheet if you do not already have them listed.
Parallel Lines – lines in the same plane that never intersect
Transversal – a line intersecting two or more other lines
Congruent angles – angles with the same measure
Vertical angles - angles formed when two lines cross; opposite angles are congruent
Supplementary – a pair of angles whose sum is 180°
Conjecture – a conclusion based on something observed
Directions:
In the figure below lines r and s are parallel and cut by transversal t.
Step 1: Copy the figure using a piece of patty paper
Step 2: Use your patty paper tracing and the original figure to determine the relationships between the angles
listed on the tables that follow. Use the terms congruent, supplementary, or cannot determine to identify the
relationships.
Corresponding Angles:
Angles
Description of Relationship
1 and 5
4 and 8
2 and 6
3 and 7
Note that the above pairs of angles are in corresponding positions when you look at the top set compared to the
bottom set of angles.
Write a conjecture about the relationship between corresponding angles formed when a pair of parallel lines is
cut by a transversal.
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Alternate Interior Angles:
Angles
Description of Relationship
3 and 5
4 and 6
Note that the pairs of angles listed are on the INTERIOR of the parallel lines and on opposite sides of the
transversal.
Write a conjecture about the relationship between alternate interior angles formed when a pair of parallel lines
is cut by a transversal.
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Alternate Exterior Angles:
Angles
1 and 7
Description of Relationship
2 and 8
Note that the pairs of angles listed are on the EXTERIOR of the parallel lines and on the opposite sides of the
transversal.
Write a conjecture about the relationship between alternate exterior angles formed when a pair of parallel lines
is cut by a transversal.
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Supplementary Angles:
Angles
2 and 3
Description of Relationship
5 and 6
Can you name some other pairs of supplementary
angles?
Vertical Angles:
Angles
2 and 4
Description of Relationship
5 and 7
Can you name two other pairs of vertical angles?
Take a few minutes to add the following to your vocabulary page along with your own descriptions.
Alternate Interior Angles, Alternate Exterior Angles, and Corresponding Angles
WHOLE CLASS ACTIVITY:
Use a protractor to measure 5 then complete the table below WITHOUT using a protractor, giving reasons for
each measure that you list. Use the relationships explored above in your reasoning. You do not have to go in any
particular order. For m< 5 your reason can be “GIVEN MEASUREMENT”.
ANGLE
1
2
3
4
5
6
7
8
Measurement in
Degrees
REASON