Exercise 24 Page 525

The distance between a point and a line is the shortest length between them. This is the measure of the line segment which passes through the point while being perpendicular to the line. Below we see three different points and their corresponding perpendicular segments. Note that the three segments have different lengths.

Is there a constant distance between the two lines? No. This means your friend is incorrect. We can only define the distance between two lines when the distance is constant — when the lines are parallel.