Parallel Lines and Transversals

Congruent Angles

• Angles that have the same measurement

Parallel Lines

• Two lines that always stay the same distance apart. (they never touch)

Perpendicular Lines

• Cross perfectly so that all four angles are 90 degrees

Transversal• Intersects two parallel lines to form many

sets of congruent angles. We have special names for these relationships

transversal

Vertical Angles

• All vertical angles are congruent • (they have the same measurement)

12

3 4

Angles 1 and 2 are vertical angles. So are angles 3 and 4

See if you can spot them

12

34

Angles 1 and 3, and angles 2 and 4

Corresponding angles

• When you draw parallel lines and a transversal, these angles have the same measure and position on each line

Corresponding angles

Alternate Interior Angles

Alternate Interior angles

Key Words: Alternate and Interior

Alternate Exterior Angles

Alternate Exterior angles

Key Words: Alternate and Exterior

Consecutive Interior Angles

Consecutive Interior angles

Key Words: Consecutive and Interior

Finding Missing Angles

• If you are given one angle measurement, you can find the rest of the measurements using the relationships.

40°

130°