(20 12? Jingzhou simulation) As shown in the figure, the two right-angle sides of Rt△ABC are 3 and 4 respectively, the straight line d E intersects with right-angle sides AC and BC in D and E respecti

(20 12? Jingzhou simulation) As shown in the figure, the two right-angle sides of Rt△ABC are 3 and 4 respectively, the straight line d E intersects with right-angle sides AC and BC in D and E respectively, and△ △CDE follows DE. In Rt△ABC, AC=4cm, BC = 3cm；;

From Pythagorean Theorem: AB = AB2+BC2 = 5cm；;

So the perimeter of the shadow part = DF+EF+AB = AB+AC+BC = 3+4+5 =12cm.

So choose C.