4. As shown in Figure 5, square $E F G H$ is inscribed in $\triangle A B C$, with $B C=\overline{a b}$ (this is a two-digit number), $E F=c$, and the height of the triangle $A D=d$.
It is known that $a$, $b$, $c$, and $d$ are exactly four consecutive positive integers in ascending order. Try to find the area of $\triangle A B C$.
(1997, Anhui Province Junior High School Mathematics Competition)
Given $\triangle A E F \backsim \triangle A B C$, we have
$$
\frac{E F}{B C}=\frac{A D-E F}{A D},
$$

which means $\frac{c}{10 a+b}=\frac{d-c}{d}$.
Also, $b=a+1, c=a+2, d=a+3$, substituting into the equation
(1) yields $a_{1}=1, a_{2}=5$.
Thus, $B C=12$ or $56 ; d=4$ or 8.
Therefore, $S_{\triangle A B C}=\frac{1}{2} B C \cdot A D=24$ or 224.