Transversal of parallel lines

Learning Objectives Identify parallel lines and transversal lines in geometric diagrams. Define and locate corresponding angles formed by a transversal cutting parallel lines. Define and locate alternate interior angles formed by a transversal cutting parallel lines. Define and locate alternate exterior angles formed by a transversal cutting parallel lines. Define and locate consecutive interior angles (same-side interior) formed by a transversal cutting parallel lines. State the relationships (equal or supplementary) between these angle pairs when lines are parallel. Find the measure of an unknown angle using the relationships of angles formed by a transversal of parallel lines. Have you ever noticed the stripes on a zebra or the tracks of a train? 🦓🚂 What happens when...

TermDefinitionExample Parallel LinesLines that are always the same distance apart and will never meet, no matter how far they are extended. They are often marked with arrows on the lines to show they are parallel.The two long sides of a ruler are parallel lines. The opposite sides of a rectangle are also parallel. Transversal LineA line that intersects two or more other lines at different points.Imagine two parallel train tracks. A road that crosses both tracks is a transversal line. Corresponding AnglesAngles that are in the 'same position' at each intersection when a transversal cuts two lines. One is usually outside and one is inside, but on the same side of the transversal.If you have two intersections, the top-left angle at the first intersection and the top-left angle at t...

Corresponding Angles Rule If two parallel lines are cut by a transversal, then corresponding angles are equal. $\angle A = \angle B$ Use this rule when you have two parallel lines and a transversal, and you need to find the measure of an angle that is in the same relative position as a known angle at the other intersection. Alternate Interior Angles Rule If two parallel lines are cut by a transversal, then alternate interior angles are equal. $\angle C = \angle D$ Apply this rule when you have two parallel lines and a transversal, and you need to find an angle that is between the parallel lines and on the opposite side of the transversal from a known angle. Alternate Exterior Angles Rule If two parallel lines are cut by a transversal, then alternate exterior angles are...