$$
\begin{array}{r}
\text { 2. } \triangle A B C \text { has side lengths of } \\
\text { 4, 5, and 6. } \triangle A^{\prime} B^{\prime} C^{\prime} \sim \triangle A B C,
\end{array}
$$
$$
\begin{array}{l}
\text { If the difference between the longest and shortest } \\
\text { sides of } \triangle A^{\prime} B^{\prime} C^{\prime} \text { is } 1 \text {. Then the area of } \triangle A^{\prime} B^{\prime} C^{\prime}
\end{array}
$$
_. $\qquad$
2. $\frac{15}{16} \sqrt{7}$