[ Perimeter of a Triangle ]

A large triangle is divided by three bold segments into four triangles and three quadrilaterals. The sum of the perimeters of the quadrilaterals is 25 cm. The sum of the perimeters of the four triangles is 20 cm. The perimeter of the original large triangle is 19 cm. Find the sum of the lengths of the bold segments.
The sum of the perimeters of all triangles and quadrilaterals is equal to the perimeter of the large triangle plus twice the sum of the lengths of the bold segments. Therefore, this sum is equal to $(25 + 20 - 19) : 2 = 13$.

## Answer

13 cm.