Angles in Parallel Lines Flashcards

All 6 cards in this deck

What are corresponding angles on parallel lines, and how are they related?

Angles in the same position at each intersection (an "F" shape) — corresponding angles are equal.

What are alternate angles on parallel lines, and how are they related?

Angles on opposite sides of the transversal, both between the parallel lines (a "Z" shape) — alternate angles are equal.

What are co-interior (allied) angles on parallel lines, and how are they related?

Angles on the same side of the transversal, both between the parallel lines (a "C" shape) — they add up to $180^\circ$.

True or false? Co-interior (allied) angles on parallel lines are equal.

False. They add up to $180^\circ$; it is alternate and corresponding angles that are equal.

True or false? Two angles on opposite sides of the transversal and both between the parallel lines are corresponding angles.

False. They are alternate angles.

What are the steps to find an unknown angle on parallel lines and justify it?

e.g. find the angle alternate to a given angle of $65^\circ$

1. Spot the shape: "Z" shape, so the angles are alternate
2. Apply the rule: alternate angles are equal, so the angle is $65^\circ$
3. Write the reason: alternate angles are equal