Within 7 cm, the first row can cut 3 pieces from one side, and the second row can also cut 3 pieces in half a circle (just to the other side). . . * * * You can cut 7 rows.

The center distance of each row is 1.732 cm, and the center distance of the first row and the last row is 1 cm, which can be calculated as follows:

(12.4-1-1)1.732 = 6, so 7 lines can be cut.