Download 3-5 Proving Lines are Parallel

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Adv Geometry
3-5 Proving Lines are Parallel
Warm Up
3-5 Proving Lines are Parallel
Postulate:
If 2 lines in a plane are cut by a transversal so that the corresponding angles are
congruent, then the lines are parallel.
Euclid’s Parallel Postulate:
If given a line and a point not on the line, there exists exactly one line through the
point that is parallel to the given line.
Theorems:
 If 2 lines in a plane are cut by a transversal so that a pair of alternate exterior
angles is congruent, then the two lines are parallel.
 If 2 lines in a plane are cut by a transversal so that a pair of consecutive
interior angles is supplementary, then the lines are parallel.
 If 2 lines in a plane are cut by a transversal so that a pair of alternate interior
angles is congruent, then the lines are parallel.
 In a plane, if 2 lines are perpendicular to the same line, then they are parallel.
Example #1
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Adv Geometry
3-5 Proving Lines are Parallel
Example #2 (p.174)
Find x and mRSU so that m || n
Name _________________________________ Date _____________ Period _________
Adv Geometry
3-5 Proving Lines are Parallel
Example:
Determine if 𝑔||𝑓. Explain.
Class work:
p. 175 #1-5, 7
Homework:
p. 176 #8-20