For reference: In the figure, find $\frac{r}{PH}$
My progress.
I found that the figure represents the Pappus chain.Pappus Chain
therefore :
The height $h_n$ of the center of the $n_th$ circle above the base diameter $ACB$ equals $n$ times $d_n$. $\therefore PH=4.2r \implies \frac{r}{PH}=\frac{r}{4r}=\frac{1}{4}$
Is this resolution correct? Is there another alternative for the resolution?