【Question 3】As shown in the figure, points $C$, $E$, and $B$ are collinear, $C B \perp A B$, $A E / / D C$, $A B=8$, $C E=5$, then the area of $\triangle A E D$ is $\qquad$.

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Geometry, equal area transformation.
Connect $A C$;
Since $A E / / D C$;
Therefore, $S_{\triangle A E D}=S_{\triangle A E C}$;
Since $C B \perp A B$;
Therefore, $S_{\triangle A E C}=C E \times A B \div 2=5 \times 8 \div 2=20$;

Therefore, $S_{\triangle A E D}=20$.