Hi,

I have a pair of known values $\displaystyle (a,b)$ that have the arithmetic geometric mean of $\displaystyle M(a,b)$

I have another pair of values $\displaystyle (c,d)$ which are unknown, but I do know that they have the same arithmetic geometric mean as the first two values, so that $\displaystyle M(a,b)=M(c,d)$.

Is there any way to derive c and d from this info? Or at least to narrow down the possibilities of what c and d might be?

Thanks