Transcript Objectives - Belle Vernon Area School District

3.3 Parallel Lines and Transversals
3.3 Parallel Lines & Transversals
• Define transversal, alternate interior angles,
alternate exterior angles, same-side interior
angles, and corresponding angles.
• Make conjectures and prove theorems by
using postulates and properties of parallel
lines and transversals.
3.3 Parallel Lines and Transversals
Theorems, Postulates, & Definitions
Corresponding Angles Postulate : If two lines
cut by a transversal are parallel, then
corresponding angles are congruent.
2  3
3.3 Parallel Lines and Transversals
Theorems, Postulates, & Definitions
Alternate Interior Angles Theorem:
If two lines cut by a transversal are parallel, then
alternate interior angles are congruent.
1  3
3.3 Parallel Lines and Transversals
Theorems, Postulates, & Definitions
Alternate Exterior Angles Theorem:
If two lines cut by a transversal are parallel,
then alternate exterior angles are congruent.
2  5
3.3 Parallel Lines and Transversals
Theorems, Postulates, & Definitions
Same-Side Interior Angles Theorem:
If two lines cut by a transversal are parallel, then
same-side interior angles are supplementary.
1 + 4 = 180
GSP Example
3.3 Parallel Lines and Transversals
Key Skills
Identify special pairs of angles.
Corresponding angles
Alternate interior angles
1 and 5
1 and 3
Same-side interior angles
1 and 4
Alternate exterior angles
2 and 5
3.3 Parallel Lines and Transversals
Key Skills
Find angle measures formed by parallel lines
and transversals.
m || n and m1 = 135°.
Then m2 = m3 = m5 = 135° and m4 = 45°.