1. 3.1 – Identify Pairs of Lines and Angles
Parallel Lines: two lines are parallel if they do not intersect AND are coplanar
Skew Lines: Two lines are skew lines if they do not intersect and ARE NOT coplanar.
Parallel Planes: Two planes are parallel if they do NOT intersect.

2. 3.1 – Identify Pairs of Lines and Angles

3. 3.1 – Identify Pairs of Lines and Angles
Example 1:
Think of each segment in the figure as part of a line. Which line(s) or plane(s) in the figure appear to fit the description?
Line(s) // to Line CD and
containing point A
Line(s) skew to Line CD and
containing point A.

4. 3.1 – Identify Pairs of Lines and Angles
Example 1:
Think of each segment in the figure as part of a line. Which line(s) or plane(s) in the figure appear to fit the description?
Line(s) perpendicular to Line CD
and containing point A.
Plane(s) parallel to plane EFG

5. 3.1 – Identify Pairs of Lines and Angles
PARALLEL AND PERPENDICULAR LINES
Through a point not on a line,
there are infinitely many lines.
Exactly one parallel.
Exactly one perpendicular.

6. 3.1 – Identify Pairs of Lines and Angles

7. 3.1 – Identify Pairs of Lines and Angles
Example 2:
The figure shows a swing set on a playground.
Name a pair of perpendicular lines.
Name a pair of parallel line.
Is Line DH perp to Line LM? Explain?

8. 3.1 – Identify Pairs of Lines and Angles
A transversal is a line that intersects two or more coplanar lines at different points.

9. 3.1 – Identify Pairs of Lines and Angles
Example 3:
Identify all pairs of angles of the given type.
Corresponding
Alternate Interior
Alternate Exterior
Consecutive Interior

10. 3.1 – Identify Pairs of Lines and Angles
Example 4:
Classify the pair of numbered angles.
a b. c.