2.1 Geometry Flashcard: Properties of Parallel Lines

Front

What are parallel lines?

Back

Parallel lines are lines in a plane that never meet. They are always the same distance apart and have the same slope.

Front

What are corresponding angles?

Back

Corresponding angles are pairs of angles that are in similar positions at each intersection where a straight line crosses two others. If the lines are parallel, corresponding angles are equal.

Front

What are alternate interior angles?

Back

Alternate interior angles are pairs of angles that lie between two lines and on opposite sides of a transversal. If the lines are parallel, alternate interior angles are equal.

Front

What are complementary angles?

Back

Complementary angles are two angles whose measures add up to 90 degrees.

Front

What are supplementary angles?

Back

Supplementary angles are two angles whose measures add up to 180 degrees.

Front

If m∠4 = 35, find m∠3. Explain.

Back

m∠3 = 55; ∠3 and ∠4 are complementary angles, so m∠3 = 90 − m∠4.

Front

If m∠4 = 35, find m∠2. Explain.

Back

m∠2 = 35; ∠2 and ∠4 are alternate interior angles, so m∠2 = m∠4.

Front

What is the sum of angles in a triangle?

Back

The sum of the interior angles in a triangle is always 180 degrees.

Front

What is a transversal?

Back

A transversal is a line that crosses at least two other lines. It creates angles that can be classified as corresponding, alternate interior, and alternate exterior.

Front

If two parallel lines are cut by a transversal, what can be said about the alternate exterior angles?

Back

If two parallel lines are cut by a transversal, the alternate exterior angles are equal.