76. On the side $C B$ of triangle $A B C$, a point $D$ is taken such that $|C D|=\alpha|A C|$. The radius of the circumcircle of $\triangle A B C$ is $R$. Find the distance between the center of the circumcircle of $\triangle A B C$ and the center of the circumcircle of $\triangle A D B$.
76. Prove that if $O$ and $O_{1}$ are the centers of the circumcircles of $\triangle A B C$ and $\triangle A D B$, then $\triangle A O O_{1}$ is similar to $\triangle A C D$.

Answer: $\alpha R$.