Suppose the correlation between vectors $A$ and $C$ of size $N$ is some value $r_{AC}$, and likewise for $B$, $C$, and $r_{BC}$. What is the distribution for $r_{AB}$?
Because correlations are cosines of angles between unit vectors, it is easy enough to compute the minimum and maximum potential values for $r_{AB}$. I have an intuition that this can be extended by calculating (analytically) the distribution of angles from some vector to some hypersphere, but I don't know how to start.