MathNet 2014 Question 11

Let $O_{1}$ and $O_{2}$ be concentric circles with radii $4$ and $6$, respectively. A chord $AB$ is drawn in $O_{1}$ with length $2$. Extend $AB$ to intersect $O_{2}$ in points $C$ and $D$. Find $CD$.



Supplemental illustration; no additional hypothesis is imposed.