Calculate Alpha Angle: Using Parallel Lines and 55-Degree Reference

Question

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

00:00 Calculate A

00:03 Parallel lines according to the given data

00:06 Alternate angles between parallel lines are equal

00:09 The angles sum to 180° (supplement to a straight angle)

00:14 Let's sum and equate to 180

00:19 Let's isolate angle A

00:27 And this is the solution to the question

125°