Question

The angle between two lines is 45° and the slope of one of the lines is 2/3. What is the slope of other lines?

Answer 1

Answer:

The slope of a line — defined as vertical change divided by horizontal change between 2 points on that line — is also the tangent of the angle between your line & the x axis. For line L1, that angle is arctan (2/3) , also known as “inverse tangent of 2/3” (a bit over 33 degrees in reality, but we don’t need to care about its measure in degrees; we get a more precise final result if we stick with arctan(2/3) for the purposes of this calculation