11. (10 points) 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】As shown in the figure: Draw a line $G F$ through point $F$ parallel to $A D$, then triangle $A G F$ is half the area of rectangle $A G F D$; triangle $G E F$ is half the area of rectangle $G B C F$, so the area of quadrilateral $A G E F$ is half the area of rectangle $A B C D$; the area of the shaded part equals the area of quadrilateral $A G E F$ minus the area of triangle $A G E$, and the solution can be found by substituting the data accordingly.
【Solution】According to the analysis:
The area of quadrilateral $A G E F$ is: $56 \div 2=28$ (square centimeters),
then the area of the shaded part is:
$$
\begin{array}{l}
28-2 \times 3 \div 2 \\
=28-3 \\
=25 \text { (square centimeters). }
\end{array}
$$

Answer: The area of triangle $A E F$ is 25 square centimeters.