1. Geometry 3.1, 3.2 and 3.3
Brit Caswell

2. Parallel lines are coplanar lines that do not intersect
Parallel lines are coplanar lines that do not intersect. This symbol means “is parallel to”.

3. Parallel planes are planes that do not intersect.

4. Skew lines are noncoplanar; they are not parallel and do not intersect.

5. A transversal is a line that intersects two or more coplanar lines at distinct points.

6. If And Only If Statements
If and only if statements (iff) are statements that are true if one side of the statement is true. “If it is raining outside, I will take my umbrella.” “If I have my umbrella, _______________.” “I will take my umbrella with me if and only if it is raining.”

7. Alternate Interior Angles
Alternate Interior Angles are nonadjacent interior angles that lie on an opposite side of the transversal.
Theorem 3.1 states that the
lines crossed by a transversal
are parallel if and only if the AIA are congruent.

8. Same-side Interior Angles
Same-side interior angles are interior angles that lie on the same side of the transversal.
Two lines being crossed
by a transversal are parallel if
and only if the SSIA are
supplementary.

9. Corresponding Angles
Corresponding angles lie on the same side of the transversal and in corresponding positions.
Theorem 3.2 states that
corresponding angles are
congruent if and only if the
lines being crossed by the
transversal are parallel.

10. Alternate Exterior Angles
Alternate exterior angles are nonadjacent exterior angles that lie on opposite sides of the transversal.
Theorem 3.3 states that
the transversal crosses
two parallel lines if and only
if the AEA are congruent.

11. Postulate
If two parallel lines are crossed by a transversal, then their corresponding angles are congruent.

12. I Do
Using your knowledge of the relationships of angles shown today, determine the value of the marked angles. 1 4 2 5 3
45˚

13. We Do (Pg 145, #37-41)
Determine whether each statement is always, sometimes, or never true.
Two parallel lines are coplanar
Two skew lines are coplanar
Two planes that do not intersect are parallel
Two lines that lie in parallel planes are parallel
Two lines in intersecting planes are skew

14. You Do (Exit Ticket)
Using your knowledge of the relationships shown over the past few days, determine the values of the marked angles, if possible. 3
130˚ 1 4 5 2