Khan Academy
Angles, Parallel Lines & Transversals
Corresponding and alternate angle relationships.
Watch on YouTubeFind angle measures when a transversal crosses parallel lines.
Read this first — it covers the idea in plain language with a worked example.
Two parallel lines are cut by a transversal. One angle is 65°. Find its corresponding angle.
Tip
The angles in a triangle add to 180°. This connects to parallel-line angle facts in many problems.
A short video that walks through this topic.
Corresponding and alternate angle relationships.
Watch on YouTubeTry a worksheet or work through some problems before the quiz.
A couple of questions to make sure this topic stuck. Retake as many times as you want.
Angles & Parallel Lines
Parallel lines are cut by a transversal. An angle measures 110°. Its alternate interior angle is: