Proving Lines Parallel

Front

What is the definition of parallel lines?

Back

Two lines that never intersect and are always the same distance apart.

Front

What is a transversal?

Back

A line that intersects two or more lines at different points.

Front

What are alternate interior angles?

Back

Angles that are on opposite sides of the transversal and inside the two lines.

Front

What are corresponding angles?

Back

Angles that are in the same position on two different lines cut by a transversal.

Front

What is the Consecutive Interior Angles Theorem?

Back

If two parallel lines are cut by a transversal, then each pair of consecutive interior angles is supplementary.

Front

What is the Alternate Interior Angles Theorem?

Back

If two parallel lines are cut by a transversal, then each pair of alternate interior angles is congruent.

Front

Back

Lines r and s are parallel by the Consecutive Interior Angles Theorem.

Front

What is the relationship between angles formed by a transversal and parallel lines?

Back

Certain pairs of angles (alternate interior, corresponding, etc.) will be congruent or supplementary.

Front

What are vertical angles?

Back

Angles that are opposite each other when two lines intersect; they are always congruent.

Front

Back

Lines l and m are parallel by the Corresponding Angles Postulate.