3.2 BUILDING ON 3.1…
Relationships for angle pairs of parallel lines with a
transversal:
corresponding angles
alternate interior angles
alternate exterior angles
same-side interior angles (consecutive interior)
same-side exterior angles (consecutive exterior)
Theorem 3.1: Corresponding Angles Theorem
NOTE: Many textbooks state this as a postulate
however this author argues that a parallel line
is a rigid transformation and thus the angles
are also a rigid transformation.
Example 1: Using the Corresponding Angles
Postulate
Find each angle measure.
A. mECF
B. mDCE
Check It Out! Example 1
Find mQRS.
3-2
3-3
3-4
Proofs for these theorems?
Example 2: Finding Angle Measures
Find each angle measure.
A. mEDG
B. mBDG
Check It Out! Example 2
Find mABD.
Example 3: Music Application
Find x and y in the diagram.
Lesson Quiz
State the theorem that is related to the
measures of the angles in each pair. Then
find the unknown angle measures.
1. m1 = 120°, m2 = (60x)°
2. m2 = (75x – 30)°,
m3 = (30x + 60)°
3. m3 = (50x + 20)°, m4= (100x – 80)°
4. m3 = (45x + 30)°, m5 = (25x + 10)°