Download Geometry 3.2

GEOMETRY 3.2
Brett Solberg
AHS ‘11-’12
WARM-UP
 Solve for x. Justify your answer.
3x - 5
x + 55
TODAY’S AGENDA
Proving Lines are Parallel.
Converses
REVIEW
Example 1
48
Example 2
120
REVIEW
 If the lines are parallel, then angles 1 and 2 are congruent.
1
2
 What if we don’t know that the lines are parallel, but that
angles 1 and 2 are congruent. What does that tell us about
the lines?
CONVERSE
 If a transversal intersects two parallel lines, then the
corresponding angles are congruent.
1
2
 Converse
 If two lines and a transversal form corresponding angles that
are congruent, then the two lines are parallel.
WRITE THE CONVERSE
 1) If a transversal intersects two parallel lines, then alternate
interior angles are congruent.
 2) If a transversal intersects two parallel lines, then same side interior angles are supplementary.
 3) If a transversal intersects two parallel lines, then alternate
exterior angles are congruent.
 4) If a transversal intersects two parallel lines, then same side exterior angles are supplementary.
EXAMPLE 3
 Find the value of x which will make a parallel to b.
42˚
a
2x + 6
b
WORKSHEET #2
Lines l and m are parallel.
Lines n and o are not parallel.
WORKSHEET #3
x + x = 180
2x = 180
x = 90
Lines i and o are parallel.
Lines v and d are parallel.
WORKSHEET #13
Corresponding Angles
2x – 75 + 2x – 20 + x + 35 = 180
5x – 60 = 180
5x = 240
x = 48
CLASS ASSIGNMENT
Worksheet 3.2 (skip #1)
Extra Credit
Challenge Assignment (10 points)