6. As shown in Figure $1, \odot O_{1}$

intersects with $\odot O_{2}$ at points $A$ and $B$,
point $C$ is on $\odot O_{1}$,
outside $\odot O_{2}$, the extensions of $C A$ and
$C B$ intersect $\odot O_{2}$ at points $D$ and
$E, \odot O_{1}$ has a radius of
$5, A C=8, A D=12, D E=14, S_{\triangle C D E}=112$. Then the radius of $\odot O_{1}$ is ( ).
(A) 5
(B) 4
(C) 6
(D) $\frac{11}{2}$
6. A.

As shown in Figure 7, draw the diameter $C F$ of $\odot O_{1}$, extend $C F$ to intersect $D E$ at point $G$, and connect $A B, A F$.
$$
\begin{array}{l}
\text { Then } \angle A F C=\angle A B C=\angle D, \\
\angle A C F=\angle G C D .
\end{array}
$$

Therefore, $\triangle A C F \backsim \triangle G C D$
$$
\Rightarrow \angle C G D=\angle C A F=90^{\circ} \text {. }
$$

Thus, $C G=\frac{2 S_{\triangle C D E}}{D E}=16$.
$$
\text { By } \frac{C F}{A C}=\frac{C D}{C G} \Rightarrow \frac{2 O_{1} C}{8}=\frac{20}{16} \Rightarrow O_{1} C=5 \text {. }
$$

Therefore, the radius of $\odot O_{1}$ is 5.