What is the measure of each line when a line of 7 cm is divided into two parts by constructing a perpendicular bisector through it?

First, a line PQ of 7 cm is drawn and then an arc from point P is drawn. 

Next, another arc is drawn from point Q. 

A line is then drawn from the point where these two intersections of the arc meet, which is line AB. 

So, point O becomes the center of the 7 cm line. 

Thus, OP = OQ = 3.5 cm which we measure using a ruler.

When a line of 7 cm is divided into two equal parts by constructing a perpendicular bisector, each part will be half the length of the original line. The perpendicular bisector creates two segments of equal length.

So, each part will be $\frac{7}{2}$= 3.5 cm in length. Therefore, each line segment formed by the perpendicular bisector will measure 3.5 cm.