Calculate Angle α: Parallel Lines with 120° Intersection Problem

Question

Calculate the angle $\alpha$ given that the lines in the diagram below are parallel.

00:00 Calculate A

00:04 Parallel lines according to the given

00:08 Alternate angles are equal between parallel lines

00:11 The angles sum to 180 (supplement to a straight angle)

00:19 Isolate A

00:22 And this is the solution to the question

60°