11. As shown in the figure, the area of rectangle $A B C D$ is $56 \mathrm{~cm}^{2}, B E=3 \mathrm{~cm}, D F=2 \mathrm{~cm}$. Please answer: What is the area of triangle $A E F$?
【Analysis】Draw a line through point $\mathrm{F}$ parallel to $\mathrm{AD}$, intersecting $\mathrm{AB}$ at point $\mathrm{G}$; connect $\mathrm{GE}$; as shown in the figure below: Quadrilateral $\mathrm{AGEF}$ is half of a rectangle, the area of triangle $\mathrm{AEF}$ is $\frac{56}{2}-\frac{2 \times 3}{2}=25$.
【Answer】 25