If the line segment bisector divides Andy's original line segment into two equal pieces, and each piece is 2.9 centimeters long, then the total length of the original line segment can be calculated by adding the lengths of the two pieces together.
Length of original line segment = Length of one piece × 2 Length of original line segment = 2.9 cm × 2 = 5.8 cm
Therefore, the length of Andy's original line segment is 5.8 cm.