2.9 - Proving Parallel Lines

Front

What are parallel lines?

Back

Lines in a plane that never meet and are always the same distance apart.

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

What is the Corresponding Angles Postulate?

Back

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

Front

What are Vertical Angles?

Back

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

Front

If m∠ABC = 40°, what is the measure of the corresponding angle when lines are parallel?

Back

40°.

Front

Solve for x: If lines l and m are parallel and m∠1 = 3x + 10, m∠2 = 5x - 2, find x.

Back

x = 22.

Front

What is the definition of Transversal?

Back

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

Front

If lines l // m and r // s, why are ∠5 & ∠15 congruent?

Back

Alternate Exterior Angles.

Front

Solve for y: If m∠A = 2y + 5 and m∠B = 3y - 10, and they are supplementary, find y.

Back

y = 31.

Front

What is the definition of Supplementary Angles?

Back

Two angles whose measures add up to 180°.