Warm Up

1
Warm Up Identify each angle pair. 1. ?1 and
?3 2. ?3 and ?6 3. ?4 and ?5 4. ?6 and ?7
corr. ?s
alt. int. ?s
alt. ext. ?s
same-side int ?s
Why did the parallel lines not recognize each
other?
2
Because they had never met?
Objective
Prove and use theorems about the angles formed by
parallel lines and a transversal.
3
(No Transcript)
4
(No Transcript)
5
(No Transcript)
6
Example 1 Using the Corresponding Angles
Postulate
Find each angle measure.
A. m?ECF
m?ECF 70
B. m?DCE
5x 4x 22
x 22
m?DCE 5x
5(22)
110
7
Check It Out! Example 1
Find m?QRS.
x 118
m?QRS 118 180
Def. of Linear Pair
m?QRS
62
8
Find the measure of angles 1, 2, 3, and 4.
9
Check It Out! Example 2
Find m?ABD.
x 25
m?ABD 2(25) 10 60
10
Example 3 Music Application
Find x and y in the diagram.
By the Alternate Interior Angles Theorem, (5x
4y) 55.
By the Corresponding Angles Postulate, (5x 5y)
60.
5x 5y 60 (5x 4y 55) y 5
Subtract the first equation from the second
equation.
5x 5(5) 60
x 7, y 5
11
Check It Out! Example 3
Find x and y in the diagram.
By the Alternate Exterior Angles Theorem, (25x
5y) 125.
By the Corresponding Angles Postulate, (25x
4y) 120.
X 4, y 5
12
(No Transcript)