14. (12 points) As shown in the figure, a rectangle is divided into 4 smaller rectangles, where the perimeters of rectangles $A$, $B$, and $C$ are 10 cm, 12 cm, and 14 cm, respectively. The maximum area of rectangle $D$ is $\qquad$ square centimeters.
【Answer】Solution: The perimeter of $D$ is: $12+14-10=16$ (cm), when $D$ is a square, its area is maximized,

side length is: $16 \div 4=4$ (cm),
area is: $4 \times 4=16$ (square cm);
Answer: The maximum area of rectangle $D$ is 16 square cm.
Therefore, the answer is: 16.