In this exercise we want to use the given diagram to name two lines. Lines in the plane are represented by a line segment with arrows on both ends. We can identify two lines in the diagram: one that goes through points B and C, and one that goes through points D and E. Let's consider the given diagram and mark these lines and points.
We can use any two points on a line to name it. Point B and C are on the first line, so we can name it BC. The order of B and C does not matter and is, therefore, an arbitrary choice. By the same principle, one name for the second line is DE.
Extra
Alternative Answers
We have stated before that to name a line we can use any two points from this line. The first line in our diagram goes through points B and C. In the name of the line the order of these points does not matter. As the example answer to the exercise we chose name BC, but name CB is also correct. Analogically, name ED for the second line is correct too.
