Construct a line segment of length 5.6 cm using ruler and compasses.

With the use of ruler and compass, we may draw the required line segment:

Step I: Draw any line L of suitable lengths.
Step II: Place the needle of the compass on the zero mark of the ruler and open it by 5.6 cm.
Step III: Place the needle at any point A at the line and draw an arc to cut l at B.

Thus, $\overline{AB}$ is the required line segment of length 5.6 cm.