5. As shown in the figure, a large triangle $A B C$ is divided into seven parts by three line segments, four of which are triangles and the other three are quadrilaterals. The sum of the perimeters of the three quadrilaterals is 25 cm, the sum of the perimeters of the four triangles is 20 cm, and the perimeter of triangle $A B C$ is 19 cm. Then $A D+B E+C F=$ $\qquad$ cm
【Answer】 13

【Solution】 If we add the sum of the perimeters of the three quadrilaterals and the sum of the perimeters of the four triangles, then the middle segments are all added twice. For example, in the figure below, $GH$ is both a side of quadrilateral $GF BH$ and a side of $\triangle GHI$. And $AB, BC, CA$ each appear only once, for example, $AF + BF = AB$. Therefore, the sum of the required segments is $(25 + 20 - 19) \div 2 = 13$ cm.