Constructing a Parallel Line through an Inaccessible Point

Given a straight line and two lines and that intersect at an inaccessible point , construct a straight line through parallel to . You can drag or .

The general method for solving this problem is to use a transformation so that the inaccessible point becomes the accessible point . In this case, the transformation is a translation in the direction of .

Using the slider, translate and parallel to to and such that the corresponding translates of and intersect at the accessible point .